Aqueous photolysis of niclosamide

USGS Publications Warehouse

Graebing, P.W.; Chib, J.S.; Hubert, T.D.; Gingerich, W.H.

2004-01-01

The photodegradation of [14C]niclosamide was studied in sterile, pH 5, 7, and 9 buffered aqueous solutions under artificial sunlight at 25.0 A? 1.0 A?C. Photolysis in pH 5 buffer is 4.3 times faster than in pH 9 buffer and 1.5 times faster than in pH 7 buffer. In the dark controls, niclosamide degraded only in the pH 5 buffer. After 360 h of continuous irradiation in pH 9 buffer, the chromatographic pattern of the degradates was the same regardless of which ring contained the radiolabel. An HPLC method was developed that confirmed these degradates to be carbon dioxide and two- and four-carbon aliphatic acids formed by cleavage of both aromatic rings. Carbon dioxide was the major degradate, comprising 40% of the initial radioactivity in the 360 h samples from both labels. The other degradates formed were oxalic acid, maleic acid, glyoxylic acid, and glyoxal. In addition, in the chloronitroaniline-labeled irradiated test solution, 2-chloro-4-nitroaniline was observed and identified after 48 h of irradiation but was not detected thereafter. No other aromatic compounds were isolated or observed in either labeled test system.

An Advanced Helium Buffer Seal for the SSME, ATD Oxygen Pump

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur

2006-01-01

The present configuration of Helium Buffer Seal on the ATD oxygen pump consists of a pair of opposed carbon rings are forced axially against their containment housings. Leakage occurs through the clearance between the rings and the shaft. The total helium leakage through both sides is approximately 239 SCFM. A reduction in leakage to 50 SCFM will result in less helium storage and consequently permit a substantial increase in payload. Under Phase 1 NASA SBIR, a solid T-Ring seal was analyzed and designed that could satisfy the criteria of reducing leakage to 50 SCFM or less. The design makes maximum use of available length and employs a mid length row of hydrostatic orifaces that feed buffer helium directly into a 2 to 3 mil clearance region. The flow splits into opposite paths to buffer oxygen gas on one side and hydrogen gas on the turbine side. The seal employs opposed hydrostatic tapered land secondary seals that provide friction free support of the primary seal and allows the primary seal to follow rotor excursion and maintain concentric operating clearance . The predicted performance of the T-seal is excellent with operation at a safe film thickness of 2 to 2.5 mils and leakage less than 50 SCFM.

Experimental high-speed network

NASA Astrophysics Data System (ADS)

McNeill, Kevin M.; Klein, William P.; Vercillo, Richard; Alsafadi, Yasser H.; Parra, Miguel V.; Dallas, William J.

1993-09-01

Many existing local area networking protocols currently applied in medical imaging were originally designed for relatively low-speed, low-volume networking. These protocols utilize small packet sizes appropriate for text based communication. Local area networks of this type typically provide raw bandwidth under 125 MHz. These older network technologies are not optimized for the low delay, high data traffic environment of a totally digital radiology department. Some current implementations use point-to-point links when greater bandwidth is required. However, the use of point-to-point communications for a total digital radiology department network presents many disadvantages. This paper describes work on an experimental multi-access local area network called XFT. The work includes the protocol specification, and the design and implementation of network interface hardware and software. The protocol specifies the Physical and Data Link layers (OSI layers 1 & 2) for a fiber-optic based token ring providing a raw bandwidth of 500 MHz. The protocol design and implementation of the XFT interface hardware includes many features to optimize image transfer and provide flexibility for additional future enhancements which include: a modular hardware design supporting easy portability to a variety of host system buses, a versatile message buffer design providing 16 MB of memory, and the capability to extend the raw bandwidth of the network to 3.0 GHz.

System and Method for Network Bandwidth, Buffers and Timing Management Using Hybrid Scheduling of Traffic with Different Priorities and Guarantees

NASA Technical Reports Server (NTRS)

Bonk, Ted (Inventor); Hall, Brendan (Inventor); Smithgall, William Todd (Inventor); Varadarajan, Srivatsan (Inventor); DeLay, Benjamin F. (Inventor)

2017-01-01

Systems and methods for network bandwidth, buffers and timing management using hybrid scheduling of traffic with different priorities and guarantees are provided. In certain embodiments, a method of managing network scheduling and configuration comprises, for each transmitting end station, reserving one exclusive buffer for each virtual link to be transmitted from the transmitting end station; for each receiving end station, reserving exclusive buffers for each virtual link to be received at the receiving end station; and for each switch, reserving a exclusive buffer for each virtual link to be received at an input port of the switch. The method further comprises determining if each respective transmitting end station, receiving end station, and switch has sufficient capability to support the reserved buffers; and reporting buffer infeasibility if each respective transmitting end station, receiving end station, and switch does not have sufficient capability to support the reserved buffers.

International comparison of observation-specific spatial buffers: maximizing the ability to estimate physical activity.

PubMed

Frank, Lawrence D; Fox, Eric H; Ulmer, Jared M; Chapman, James E; Kershaw, Suzanne E; Sallis, James F; Conway, Terry L; Cerin, Ester; Cain, Kelli L; Adams, Marc A; Smith, Graham R; Hinckson, Erica; Mavoa, Suzanne; Christiansen, Lars B; Hino, Adriano Akira F; Lopes, Adalberto A S; Schipperijn, Jasper

2017-01-23

Advancements in geographic information systems over the past two decades have increased the specificity by which an individual's neighborhood environment may be spatially defined for physical activity and health research. This study investigated how different types of street network buffering methods compared in measuring a set of commonly used built environment measures (BEMs) and tested their performance on associations with physical activity outcomes. An internationally-developed set of objective BEMs using three different spatial buffering techniques were used to evaluate the relative differences in resulting explanatory power on self-reported physical activity outcomes. BEMs were developed in five countries using 'sausage,' 'detailed-trimmed,' and 'detailed,' network buffers at a distance of 1 km around participant household addresses (n = 5883). BEM values were significantly different (p < 0.05) for 96% of sausage versus detailed-trimmed buffer comparisons and 89% of sausage versus detailed network buffer comparisons. Results showed that BEM coefficients in physical activity models did not differ significantly across buffering methods, and in most cases BEM associations with physical activity outcomes had the same level of statistical significance across buffer types. However, BEM coefficients differed in significance for 9% of the sausage versus detailed models, which may warrant further investigation. Results of this study inform the selection of spatial buffering methods to estimate physical activity outcomes using an internationally consistent set of BEMs. Using three different network-based buffering methods, the findings indicate significant variation among BEM values, however associations with physical activity outcomes were similar across each buffering technique. The study advances knowledge by presenting consistently assessed relationships between three different network buffer types and utilitarian travel, sedentary behavior, and leisure-oriented physical activity outcomes.

Aqueous solution dispersement of carbon nanotubes

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

2011-01-01

Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

Buffer Management Simulation in ATM Networks

NASA Technical Reports Server (NTRS)

Yaprak, E.; Xiao, Y.; Chronopoulos, A.; Chow, E.; Anneberg, L.

1998-01-01

This paper presents a simulation of a new dynamic buffer allocation management scheme in ATM networks. To achieve this objective, an algorithm that detects congestion and updates the dynamic buffer allocation scheme was developed for the OPNET simulation package via the creation of a new ATM module.

BaRT Manual Version 3.0

DTIC Science & Technology

1991-02-14

collectio of ifnformation is eitirmate" to average Ihoar der fesporse. inciudng the time for reviwing instructions, searchi’ng estung data sources...visible field of the buffer. <Cntl>-n -- next visible field of the buffer. <Cntl>- k -- kill from point to end of buffer. <Cntl>-y -- yank from kill ring...and a button. Position the mouse on the field in front of the Name. A box will highlight this field. Click on this field. Press <cntr> k to remove the

Message communications of particular message types between compute nodes using DMA shadow buffers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blocksome, Michael A.; Parker, Jeffrey J.

Message communications of particular message types between compute nodes using DMA shadow buffers includes: receiving a buffer identifier specifying an application buffer having a message of a particular type for transmission to a target compute node through a network; selecting one of a plurality of shadow buffers for a DMA engine on the compute node for storing the message, each shadow buffer corresponding to a slot of an injection FIFO buffer maintained by the DMA engine; storing the message in the selected shadow buffer; creating a data descriptor for the message stored in the selected shadow buffer; injecting the datamore » descriptor into the slot of the injection FIFO buffer corresponding to the selected shadow buffer; selecting the data descriptor from the injection FIFO buffer; and transmitting the message specified by the selected data descriptor through the data communications network to the target compute node.« less

CMOS integrated avalanche photodiodes and frequency-mixing optical sensor front end for portable NIR spectroscopy instruments.

PubMed

Yun, Ruida; Sthalekar, Chirag; Joyner, Valencia M

2011-01-01

This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \\im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 V. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92 dS Ω conversion gain with 0.5 V modulating voltage. The measured IIP(3) is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23 mA from a1.8 V power supply.

Adaptive Video Streaming Using Bandwidth Estimation for 3.5G Mobile Network

NASA Astrophysics Data System (ADS)

Nam, Hyeong-Min; Park, Chun-Su; Jung, Seung-Won; Ko, Sung-Jea

Currently deployed mobile networks including High Speed Downlink Packet Access (HSDPA) offer only best-effort Quality of Service (QoS). In wireless best effort networks, the bandwidth variation is a critical problem, especially, for mobile devices with small buffers. This is because the bandwidth variation leads to packet losses caused by buffer overflow as well as picture freezing due to high transmission delay or buffer underflow. In this paper, in order to provide seamless video streaming over HSDPA, we propose an efficient real-time video streaming method that consists of the available bandwidth (AB) estimation for the HSDPA network and the transmission rate control to prevent buffer overflows/underflows. In the proposed method, the client estimates the AB and the estimated AB is fed back to the server through real-time transport control protocol (RTCP) packets. Then, the server adaptively adjusts the transmission rate according to the estimated AB and the buffer state obtained from the RTCP feedback information. Experimental results show that the proposed method achieves seamless video streaming over the HSDPA network providing higher video quality and lower transmission delay.

Microcomputer Applications with PC LAN (Local Area Network) in Battleships.

DTIC Science & Technology

1988-12-01

NETWORKS 5 C. TRANSMISSION TECHNIQUES 6 D. MEDIUM ACCESS CONTROL METHODS 6 1. CSMA CD 6 2. Control Token 7 3. Slotted Ring 7 E...network model in the Turkish Battleships will employ the broadband technique. D. MEDIUM ACCESS CONTROL METHODS The access method is one of the most...better performance at heavier loads. 3. Slotted Ring This method is used with a ring network. The ring is initialized to contain a fixed number of

Near-optimality of special periodic protocols for fluid models of single server switched networks with switchover times

NASA Astrophysics Data System (ADS)

Matveev, A. S.; Ishchenko, R.

2017-11-01

We consider a generic deterministic time-invariant fluid model of a single server switched network, which consists of finitely many infinite size buffers (queues) and receives constant rate inflows of jobs from the outside. Any flow undergoes a multi-phase service, entering a specific buffer after every phase, and ultimately leaves the network; the route of the flow over the buffers is pre-specified, and flows may merge inside the network. They share a common source of service, which can serve at most one buffer at a time and has to switch among buffers from time to time; any switch consumes a nonzero switchover period. With respect to the long-run maximal scaled wip (work in progress) performance metric, near-optimality of periodic scheduling and service protocols is established: the deepest optimum (that is over all feasible processes in the network, irrespective of the initial state) is furnished by such a protocol up to as small error as desired. Moreover, this can be achieved with a special periodic protocol introduced in the paper. It is also shown that the exhaustive policy is optimal for any buffer whose service at the maximal rate does not cause growth of the scaled wip.

Fibril growth kinetics link buffer conditions and topology of 3D collagen I networks.

PubMed

Kalbitzer, Liv; Pompe, Tilo

2018-02-01

Three-dimensional fibrillar networks reconstituted from collagen I are widely used as biomimetic scaffolds for in vitro and in vivo cell studies. Various physicochemical parameters of buffer conditions for in vitro fibril formation are well known, including pH-value, ion concentrations and temperature. However, there is a lack of a detailed understanding of reconstituting well-defined 3D network topologies, which is required to mimic specific properties of the native extracellular matrix. We screened a wide range of relevant physicochemical buffer conditions and characterized the topology of the reconstituted 3D networks in terms of mean pore size and fibril diameter. A congruent analysis of fibril formation kinetics by turbidimetry revealed the adjustment of the lateral growth phase of fibrils by buffer conditions to be key in the determination of pore size and fibril diameter of the networks. Although the kinetics of nucleation and linear growth phase were affected by buffer conditions as well, network topology was independent of those two growth phases. Overall, the results of our study provide necessary insights into how to engineer 3D collagen matrices with an independent control over topology parameters, in order to mimic in vivo tissues in in vitro experiments and tissue engineering applications. The study reports a comprehensive analysis of physicochemical conditions of buffer solutions to reconstitute defined 3D collagen I matrices. By a combined analysis of network topology, i.e., pore size and fibril diameter, and the kinetics of fibril formation we can reveal the dependence of 3D network topology on buffer conditions, such as pH-value, phosphate concentration and sodium chloride content. With those results we are now able to provide engineering strategies to independently tune the topology parameters of widely used 3D collagen scaffolds based on the buffer conditions. By that, we enable the straightforward mimicking of extracellular matrices of in vivo tissues for in vitro cell culture experiments and tissue engineering applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Design and evaluation of a DAMQ multiprocessor network with self-compacting buffers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.; O`Krafka, B.W.O.; Vassiliadis, S.

1994-12-31

This paper describes a new approach to implement Dynamically Allocated Multi-Queue (DAMQ) switching elements using a technique called ``self-compacting buffers``. This technique is efficient in that the amount of hardware required to manage the buffers is relatively small; it offers high performance since it is an implementation of a DAMQ. The first part of this paper describes the self-compacting buffer architecture in detail, and compares it against a competing DAMQ switch design. The second part presents extensive simulation results comparing the performance of a self compacting buffer switch against an ideal switch including several examples of k-ary n-cubes and deltamore » networks. In addition, simulation results show how the performance of an entire network can be quickly and accurately approximated by simulating just a single switching element.« less

The role of the episodic buffer in working memory for language processing.

PubMed

Rudner, Mary; Rönnberg, Jerker

2008-03-01

A body of work has accumulated to show that the cognitive process of binding information from different mnemonic and sensory sources as well as in different linguistic modalities can be fractionated from general executive functions in working memory both functionally and neurally. This process has been defined in terms of the episodic buffer (Baddeley in Trends Cogn Sci 4(11):417-423, 2000). This paper considers behavioural, neuropsychological and neuroimaging data that elucidate the role of the episodic buffer in language processing. We argue that the episodic buffer seems to be truly multimodal in function and that while formation of unitary multidimensional representations in the episodic buffer seems to engage posterior neural networks, maintenance of such representations is supported by frontal networks. Although, the episodic buffer is not necessarily supported by executive processes and seems to be supported by different neural networks, it may operate in tandem with the central executive during effortful language processing. There is also evidence to suggest engagement of the phonological loop during buffer processing. The hippocampus seems to play a role in formation but not maintenance of representations in the episodic buffer of working memory.

VORBrouter: A dynamic data routing system for Real-Time Seismic networks

NASA Astrophysics Data System (ADS)

Hansen, T.; Vernon, F.; Lindquist, K.; Orcutt, J.

2004-12-01

For anyone who has managed a moderately complex buffered real-time data transport system, the need for reliable adaptive data transport is clear. The ROADNet VORBrouter system, an extension to the ROADNet data catalog system [AGU-2003, Dynamic Dataflow Topology Monitoring for Real-time Seismic Networks], allows dynamic routing of real-time seismic data from sensor to end-user. Traditional networks consist of a series of data buffer computers with data transport interconnections configured by hand. This allows for arbitrarily complex data networks, which can often exceed full comprehension by network administrators, sometimes resulting in data loops or accidental data cutoff. In order to manage data transport systems in the event of a network failure, a network administrator must be called upon to change the data transport paths and to recover the missing data. Using VORBrouter, administrators can sleep at night while still providing 7/24 uninterupted data streams at realistic cost. This software package uses information from the ROADNet data catalog system to route packets around failed link outages and to new consumers in real-time. Dynamic data routing protocols operating on top of the Antelope Data buffering layer allow authorized users to request data sets from their local buffer and to have them delivered from anywhere within the network of buffers. The VORBrouter software also allows for dynamic routing around network outages, and the elimination of duplicate data paths within the network, while maintaining the nearly lossless data transport features exhibited by the underlying Antelope system. We present the design of the VORBrouter system, its features, limitations and some future research directions.

Active Black Holes: Relevant Plasma Structures, Regimes and Processes Involving All Phase Space*

NASA Astrophysics Data System (ADS)

Coppi, B.

2010-11-01

The presented theory is motivated by the growing body of experimental information on the characteristics, connected with relevant spectral, time and space resolutions, of the radiation emission from objects considered as rotating black holes. In the immediate surroundings of these objects three plasma regions [1] are identified: an innermost Buffer Region, an intermediate Three-regime Region and a Structured Peripheral Region. In the last region a Composite Disk Structure that is a sequence of plasma rings corresponding to closed magnetic surfaces is considered to be present and to allow intermittent accretion flows along the relevant separatrices. The non-linear ``Master Equation'' describing this structure is derived and solved in appropriate asymptotic limits. The rings structure, depending on microscopic plasma characteristics: i) can be excluded from forming in the intermediate region allowing the onset of a spiral structure with which High Frequency Quasi Periodic Oscillations are associated; ii) may be allowed to propagate to the outer edge of the Buffer Region where successive rings with opposite currents are ejected vertically (in opposite directions) and originate the observed jets; iii) is dissipated well before the Buffer Region. *Sponsored in part by the U.S. D.O.E. [1] B. Coppi, Plasmas in the Laboratory and in the Universe, Eds. G. Bertin et al. (Publ. American Institute of Physics, New York, 2010).

Identification of BVT.2938 metabolites by LC/MS and LC/MS/MS after in vitro incubations with liver microsomes and hepatocytes.

PubMed

Edlund, Per Olof; Baranczewski, Pawel

2004-03-10

The metabolism of the 5HT2c agonist BVT.2938, 1-(3-[2-[(2-ethoxy-3-pyridinyl)oxy]ethoxy]-2-pyrazinyl)-2(R)-methylpiperazine, was studied in vitro by incubation with rat, monkey and human liver microsomes as well as cryopreserved hepatocytes, followed by liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS analysis on a quadrupole-time of flight mass spectrometer for structural elucidation. Deuterium exchange on column was used to differentiate between hydroxylation and N-oxidation. Liver microsomes were incubated in two different buffer systems with optimum conditions for cytochrome P450 activity or UDP-glucuronosyltransferase activity. The major phase I metabolites of BVT.2938 originated from O-deethylation of the pyridine ring, O-dealkylation of the ethylene bridge, pyrazine ring hydroxylation, hydroxylation of pyridine ring and piperazine ring N-hydroxylation. When a hydrogen carbonate buffer system was supplemented with UDPGA, the piperazine carbamoyl-glucuronide from the parent compound was identified together with several glucuronides of the phase I metabolites. The metabolite pattern in hepatocytes was similar to microsomes except that the sulphate at the N-position of the piperazine ring of BVT.2938 was identified, while the carbamoyl-glucuronide was missing. Excellent correlation was obtained between radioactivity detection and the chemiluminescent nitrogen detector when the nitrogen content of the analytes was taken into account.

MPNACK: an optical switching scheme enabling the buffer-less reliable transmission

NASA Astrophysics Data System (ADS)

Yu, Xiaoshan; Gu, Huaxi; Wang, Kun; Xu, Meng; Guo, Yantao

2016-01-01

Optical data center networks are becoming an increasingly promising solution to solve the bottlenecks faced by electrical networks, such as low transmission bandwidth, high wiring complexity, and unaffordable power consumption. However, the optical circuit switching (OCS) network is not flexible enough to carry the traffic burst while the optical packet switching (OPS) network cannot solve the packet contention in an efficient way. To this end, an improved switching strategy named OPS with multi-hop Negative Acknowledgement (MPNACK) is proposed. This scheme uses a feedback mechanism, rather than the buffering structure, to handle the optical packet contention. The collided packet is treated as a NACK packet and sent back to the source server. When the sender receives this NACK packet, it knows a collision happens in the transmission path and a retransmission procedure is triggered. Overall, the OPS-NACK scheme enables a reliable transmission in the buffer-less optical network. Furthermore, with this scheme, the expensive and energy-hungry elements, optical or electrical buffers, can be removed from the optical interconnects, thus a more scalable and cost-efficient network can be constructed for cloud computing data centers.

Interconnecting network for switching data packets and method for switching data packets

DOEpatents

Benner, Alan Frederic; Minkenberg, Cyriel Johan Agnes; Stunkel, Craig Brian

2010-05-25

The interconnecting network for switching data packets, having data and flow control information, comprises a local packet switch element (S1) with local input buffers (I(1,1) . . . I(1,y)) for buffering the incoming data packets, a remote packet switch element (S2) with remote input buffers (I(2,1) . . . I(2,y)) for buffering the incoming data packets, and data lines (L) for interconnecting the local and the remote packet switch elements (S1, S2). The interconnecting network further comprises a local and a remote arbiter (A1, A2) which are connected via control lines (CL) to the input buffers (I(1,1) . . . I(1,y), I(2,1) . . . I(2,y)), and which are formed such that they can provide that the flow control information is transmitted via the data lines (L) and the control lines (CL).

Advanced Ring-Shaped Microelectrode Assay Combined with Small Rectangular Electrode for Quasi-In vivo Measurement of Cell-to-Cell Conductance in Cardiomyocyte Network

NASA Astrophysics Data System (ADS)

Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji

2013-06-01

To predict the risk of fatal arrhythmia induced by cardiotoxicity in the highly complex human heart system, we have developed a novel quasi-in vivo electrophysiological measurement assay, which combines a ring-shaped human cardiomyocyte network and a set of two electrodes that form a large single ring-shaped electrode for the direct measurement of irregular cell-to-cell conductance occurrence in a cardiomyocyte network, and a small rectangular microelectrode for forced pacing of cardiomyocyte beating and for acquiring the field potential waveforms of cardiomyocytes. The advantages of this assay are as follows. The electrophysiological signals of cardiomyocytes in the ring-shaped network are superimposed directly on a single loop-shaped electrode, in which the information of asynchronous behavior of cell-to-cell conductance are included, without requiring a set of huge numbers of microelectrode arrays, a set of fast data conversion circuits, or a complex analysis in a computer. Another advantage is that the small rectangular electrode can control the position and timing of forced beating in a ring-shaped human induced pluripotent stem cell (hiPS)-derived cardiomyocyte network and can also acquire the field potentials of cardiomyocytes. First, we constructed the human iPS-derived cardiomyocyte ring-shaped network on the set of two electrodes, and acquired the field potential signals of particular cardiomyocytes in the ring-shaped cardiomyocyte network during simultaneous acquisition of the superimposed signals of whole-cardiomyocyte networks representing cell-to-cell conduction. Using the small rectangular electrode, we have also evaluated the response of the cell network to electrical stimulation. The mean and SD of the minimum stimulation voltage required for pacing (VMin) at the small rectangular electrode was 166+/-74 mV, which is the same as the magnitude of amplitude for the pacing using the ring-shaped electrode (179+/-33 mV). The results showed that the addition of a small rectangular electrode into the ring-shaped electrode was effective for the simultaneous measurement of whole-cell-network signals and single-cell/small-cluster signals on a local site in the cell network, and for the pacing by electrical stimulation of cardiomyocyte networks.

Neighborhood sampling: how many streets must an auditor walk?

PubMed

McMillan, Tracy E; Cubbin, Catherine; Parmenter, Barbara; Medina, Ashley V; Lee, Rebecca E

2010-03-12

This study tested the representativeness of four street segment sampling protocols using the Pedestrian Environment Data Scan (PEDS) in eleven neighborhoods surrounding public housing developments in Houston, TX. The following four street segment sampling protocols were used (1) all segments, both residential and arterial, contained within the 400 meter radius buffer from the center point of the housing development (the core) were compared with all segments contained between the 400 meter radius buffer and the 800 meter radius buffer (the ring); all residential segments in the core were compared with (2) 75% (3) 50% and (4) 25% samples of randomly selected residential street segments in the core. Analyses were conducted on five key variables: sidewalk presence; ratings of attractiveness and safety for walking; connectivity; and number of traffic lanes. Some differences were found when comparing all street segments, both residential and arterial, in the core to the ring. Findings suggested that sampling 25% of residential street segments within the 400 m radius of a residence sufficiently represents the pedestrian built environment. Conclusions support more cost effective environmental data collection for physical activity research.

Neighborhood sampling: how many streets must an auditor walk?

PubMed Central

2010-01-01

This study tested the representativeness of four street segment sampling protocols using the Pedestrian Environment Data Scan (PEDS) in eleven neighborhoods surrounding public housing developments in Houston, TX. The following four street segment sampling protocols were used (1) all segments, both residential and arterial, contained within the 400 meter radius buffer from the center point of the housing development (the core) were compared with all segments contained between the 400 meter radius buffer and the 800 meter radius buffer (the ring); all residential segments in the core were compared with (2) 75% (3) 50% and (4) 25% samples of randomly selected residential street segments in the core. Analyses were conducted on five key variables: sidewalk presence; ratings of attractiveness and safety for walking; connectivity; and number of traffic lanes. Some differences were found when comparing all street segments, both residential and arterial, in the core to the ring. Findings suggested that sampling 25% of residential street segments within the 400 m radius of a residence sufficiently represents the pedestrian built environment. Conclusions support more cost effective environmental data collection for physical activity research. PMID:20226052

Parallel processor-based raster graphics system architecture

DOEpatents

Littlefield, Richard J.

1990-01-01

An apparatus for generating raster graphics images from the graphics command stream includes a plurality of graphics processors connected in parallel, each adapted to receive any part of the graphics command stream for processing the command stream part into pixel data. The apparatus also includes a frame buffer for mapping the pixel data to pixel locations and an interconnection network for interconnecting the graphics processors to the frame buffer. Through the interconnection network, each graphics processor may access any part of the frame buffer concurrently with another graphics processor accessing any other part of the frame buffer. The plurality of graphics processors can thereby transmit concurrently pixel data to pixel locations in the frame buffer.

Alternative parallel ring protocols

NASA Technical Reports Server (NTRS)

Mukkamala, R.; Foudriat, E. C.; Maly, Kurt J.; Kale, V.

1990-01-01

Communication protocols are know to influence the utilization and performance of communication network. The effect of two token ring protocols on a gigabit network with multiple ring structure is investigated. In the first protocol, a mode sends at most one message on receiving a token. In the second protocol, a mode sends all the waiting messages when a token is received. The behavior of these protocols is shown to be highly dependent on the number of rings as well as the load in the network.

Active black holes: Relevant plasma structures, regimes and processes involving all phase space

NASA Astrophysics Data System (ADS)

Coppi, Bruno

2011-03-01

The presented theory is motivated by the growing body of experimental information on the characteristics, connected with relevant spectral, time, and space resolutions, of the radiation emission from objects considered as rotating black holes. In the immediate surroundings of these objects, three plasma regions are identified: an innermost Buffer Region, an intermediate Three-regime Region, and a Structured Peripheral Region. In the last region, a Composite Disk Structure made of a sequence of plasma rings corresponding to the formation of closed magnetic surfaces is considered to be present and to allow intermittent accretion flows along the relevant separatrices. The nonlinear ``Master Equation'' describing composite disk structures is derived and solved in appropriate asymptotic limits. A ring configuration, depending on the state of the plasma at the microscopic level: (i) can be excluded from forming given the strongly nonthermal nature of the electron distribution (in momentum space) within the Three-regime Region allowing the onset of a spiral structure; the observed High Frequency Quasi Periodic Oscillations are associated with these tridimensional structures; (ii) may be allowed to propagate to the outer edge of the Buffer Region where successive rings carrying currents in opposite directions are ejected vertically (in opposite directions) and originate the observed jets; or (iii) penetrates in the Three-regime Region and is dissipated before reaching the outer edge of the Buffer Region. The absence of a coherent composite disk structure guiding accretion in the presence of a significant magnetic field background is suggested to characterize quiescent black holes.

Leverage Between the Buffering Effect and the Bystander Effect in Social Networking.

PubMed

Chiu, Yu-Ping; Chang, Shu-Chen

2015-08-01

This study examined encouraged and inhibited social feedback behaviors based on the theories of the buffering effect and the bystander effect. A system program was used to collect personal data and social feedback from a Facebook data set to test the research model. The results revealed that the buffering effect induced a positive relationship between social network size and feedback gained from friends when people's social network size was under a certain cognitive constraint. For people with a social network size that exceeds this cognitive constraint, the bystander effect may occur, in which having more friends may inhibit social feedback. In this study, two social psychological theories were applied to explain social feedback behavior on Facebook, and it was determined that social network size and social feedback exhibited no consistent linear relationship.

Ring correlations in random networks.

PubMed

Sadjadi, Mahdi; Thorpe, M F

2016-12-01

We examine the correlations between rings in random network glasses in two dimensions as a function of their separation. Initially, we use the topological separation (measured by the number of intervening rings), but this leads to pseudo-long-range correlations due to a lack of topological charge neutrality in the shells surrounding a central ring. This effect is associated with the noncircular nature of the shells. It is, therefore, necessary to use the geometrical distance between ring centers. Hence we find a generalization of the Aboav-Weaire law out to larger distances, with the correlations between rings decaying away when two rings are more than about three rings apart.

Tree-ring-based estimates of long-term seasonal precipitation in the Souris River Region of Saskatchewan, North Dakota and Manitoba

USGS Publications Warehouse

Ryberg, Karen R.; Vecchia, Aldo V.; Akyüz, F. Adnan; Lin, Wei

2016-01-01

Historically unprecedented flooding occurred in the Souris River Basin of Saskatchewan, North Dakota and Manitoba in 2011, during a longer term period of wet conditions in the basin. In order to develop a model of future flows, there is a need to evaluate effects of past multidecadal climate variability and/or possible climate change on precipitation. In this study, tree-ring chronologies and historical precipitation data in a four-degree buffer around the Souris River Basin were analyzed to develop regression models that can be used for predicting long-term variations of precipitation. To focus on longer term variability, 12-year moving average precipitation was modeled in five subregions (determined through cluster analysis of measures of precipitation) of the study area over three seasons (November–February, March–June and July–October). The models used multiresolution decomposition (an additive decomposition based on powers of two using a discrete wavelet transform) of tree-ring chronologies from Canada and the US and seasonal 12-year moving average precipitation based on Adjusted and Homogenized Canadian Climate Data and US Historical Climatology Network data. Results show that precipitation varies on long-term (multidecadal) time scales of 16, 32 and 64 years. Past extended pluvial and drought events, which can vary greatly with season and subregion, were highlighted by the models. Results suggest that the recent wet period may be a part of natural variability on a very long time scale.

Nonblocking Clos networks of multiple ROADM rings for mega data centers.

PubMed

Zhao, Li; Ye, Tong; Hu, Weisheng

2015-11-02

Optical networks have been introduced to meet the bandwidth requirement of mega data centers (DC). Most existing approaches are neither scalable to face the massive growth of DCs, nor contention-free enough to provide full bisection bandwidth. To solve this problem, we propose two symmetric network structures: ring-MEMS-ring (RMR) network and MEMS-ring-MEMS (MRM) network based on classical Clos theory. New strategies are introduced to overcome the additional wavelength constraints that did not exist in the traditional Clos network. Two structures that followed the strategies can enable high scalability and nonblocking property simultaneously. The one-to-one correspondence of the RMR and MRM structures to a Clos is verified and the nonblocking conditions are given along with the routing algorithms. Compared to a typical folded-Clos network, both structures are more readily scalable to future mega data centers with 51200 racks while reducing number of long cables significantly. We show that the MRM network is more cost-effective than the RMR network, since the MRM network does not need tunable lasers to achieve nonblocking routing.

Universal null DTE (data terminal equipment)

DOEpatents

George, M.; Pierson, L.G.; Wilkins, M.E.

1987-11-09

A communication device in the form of data terminal equipment permits two data communication equipments, each having its own master clock and operating at substantially the same nominal clock rate, to communicate with each other in a multi-segment circuit configuration of a general communication network even when phase or frequency errors exist between the two clocks. Data transmitted between communication equipments of two segments of the communication network is buffered. A variable buffer fill circuit is provided to fill the buffer to a selectable extent prior to initiation of data output clocking. Selection switches are provided to select the degree of buffer preload. A dynamic buffer fill circuit may be incorporated for automatically selecting the buffer fill level as a function of the difference in clock frequencies of the two equipments. Controllable alarm circuitry is provided for selectively generating an underflow or an overflow alarm to one or both of the communicating equipments. 5 figs.

Universal null DTE

DOEpatents

George, Michael; Pierson, Lyndon G.; Wilkins, Mark E.

1989-01-01

A communication device in the form of data terminal equipment permits two data communication equipments, each having its own master clock and operating at substantially the same nominal clock rate, to communicate with each other in a multi-segment circuit configuration of a general communication network even when phase or frequency errors exist between the two clocks. Data transmitted between communication equipments of two segments of the communication network is buffered. A variable buffer fill circuit is provided to fill the buffer to a selectable extent prior to initiation of data output clocking. Selection switches are provided to select the degree of buffer preload. A dynamic buffer fill circuit may be incorporated for automatically selecting the buffer fill level as a function of the difference in clock frequencies of the two equipments. Controllable alarm circuitry is provided for selectively generating an underflow or an overflow alarm to one or both of the communicating equipments.

A Bell inequality for a class of multilocal ring networks

NASA Astrophysics Data System (ADS)

Frey, Michael

2017-11-01

Quantum networks with independent sources of entanglement (hidden variables) and nodes that execute joint quantum measurements can create strong quantum correlations spanning the breadth of the network. Understanding of these correlations has to the present been limited to standard Bell experiments with one source of shared randomness, bilocal arrangements having two local sources of shared randomness, and multilocal networks with tree topologies. We introduce here a class of quantum networks with ring topologies comprised of subsystems each with its own internally shared source of randomness. We prove a Bell inequality for these networks, and to demonstrate violations of this inequality, we focus on ring networks with three-qubit subsystems. Three qubits are capable of two non-equivalent types of entanglement, GHZ and W-type. For rings of any number N of three-qubit subsystems, our inequality is violated when the subsystems are each internally GHZ-entangled. This violation is consistently stronger when N is even. This quantitative even-odd difference for GHZ entanglement becomes extreme in the case of W-type entanglement. When the ring size N is even, the presence of W-type entanglement is successfully detected; when N is odd, the inequality consistently fails to detect its presence.

Performance Evaluation of Telemedicine System based on multicasting over Heterogeneous Network.

PubMed

Yun, H Y; Yoo, S K; Kim, D K; Rim Kim, Sung

2005-01-01

For appropriate diagnosis, medical image such as high quality image of patient's affected part and vital signal, patient information, and teleconferencing data for communication between specialists will be transmitted. After connecting patient and specialist the center, sender acquires patient data and transmits to the center through TCP/IP protocol. Data that is transmitted to center is retransmitted to each specialist side that accomplish connection after being copied according to listener's number from transmission buffer. At transmission of medical information data in network, transmission delay and loss occur by the change of buffer size, packet size, number of user and kind of networks. As there lies the biggest delay possibility in ADSL, buffer Size should be established by 1Mbytes first to minimize transmission regionalism and each packet's size must be set accordingly to MTU Size in order to improve network efficiency by maximum. Also, listener's number should be limited by less than 6 people. Data transmission consisted smoothly all in experiment result in common use network- ADSL, VDSL, WLAN, LAN-. But, possibility of delay appeared most greatly in ADSL that has the most confined bandwidth. To minimize the possibility of delay, some adjustment is needed such as buffer size, number of receiver, packet size.

Capture and playback synchronization in video conferencing

NASA Astrophysics Data System (ADS)

Shae, Zon-Yin; Chang, Pao-Chi; Chen, Mon-Song

1995-03-01

Packet-switching based video conferencing has emerged as one of the most important multimedia applications. Lip synchronization can be disrupted in the packet network as the result of the network properties: packet delay jitters at the capture end, network delay jitters, packet loss, packet arrived out of sequence, local clock mismatch, and video playback overlay with the graphic system. The synchronization problem become more demanding as the real time and multiparty requirement of the video conferencing application. Some of the above mentioned problem can be solved in the more advanced network architecture as ATM having promised. This paper will present some of the solutions to the problems that can be useful at the end station terminals in the massively deployed packet switching network today. The playback scheme in the end station will consist of two units: compression domain buffer management unit and the pixel domain buffer management unit. The pixel domain buffer management unit is responsible for removing the annoying frame shearing effect in the display. The compression domain buffer management unit is responsible for parsing the incoming packets for identifying the complete data blocks in the compressed data stream which can be decoded independently. The compression domain buffer management unit is also responsible for concealing the effects of clock mismatch, lip synchronization, and packet loss, out of sequence, and network jitters. This scheme can also be applied to the multiparty teleconferencing environment. Some of the schemes presented in this paper have been implemented in the Multiparty Multimedia Teleconferencing (MMT) system prototype at the IBM watson research center.

'Trophic whales' as biotic buffers: weak interactions stabilize ecosystems against nutrient enrichment.

PubMed

Schwarzmüller, Florian; Eisenhauer, Nico; Brose, Ulrich

2015-05-01

Human activities may compromise biodiversity if external stressors such as nutrient enrichment endanger overall network stability by inducing unstable dynamics. However, some ecosystems maintain relatively high diversity levels despite experiencing continuing disturbances. This indicates that some intrinsic properties prevent unstable dynamics and resulting extinctions. Identifying these 'ecosystem buffers' is crucial for our understanding of the stability of ecosystems and an important tool for environmental and conservation biologists. In this vein, weak interactions have been suggested as stabilizing elements of complex systems, but their relevance has rarely been tested experimentally. Here, using network and allometric theory, we present a novel concept for a priori identification of species that buffer against externally induced instability of increased population oscillations via weak interactions. We tested our model in a microcosm experiment using a soil food-web motif. Our results show that large-bodied species feeding at the food web's base, so called 'trophic whales', can buffer ecosystems against unstable dynamics induced by nutrient enrichment. Similar to the functionality of chemical or mechanical buffers, they serve as 'biotic buffers' that take up stressor effects and thus protect fragile systems from instability. We discuss trophic whales as common functional building blocks across ecosystems. Considering increasing stressor effects under anthropogenic global change, conservation of these network-intrinsic biotic buffers may help maintain the stability and diversity of natural ecosystems. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

The RING 2.0 web server for high quality residue interaction networks.

PubMed

Piovesan, Damiano; Minervini, Giovanni; Tosatto, Silvio C E

2016-07-08

Residue interaction networks (RINs) are an alternative way of representing protein structures where nodes are residues and arcs physico-chemical interactions. RINs have been extensively and successfully used for analysing mutation effects, protein folding, domain-domain communication and catalytic activity. Here we present RING 2.0, a new version of the RING software for the identification of covalent and non-covalent bonds in protein structures, including π-π stacking and π-cation interactions. RING 2.0 is extremely fast and generates both intra and inter-chain interactions including solvent and ligand atoms. The generated networks are very accurate and reliable thanks to a complex empirical re-parameterization of distance thresholds performed on the entire Protein Data Bank. By default, RING output is generated with optimal parameters but the web server provides an exhaustive interface to customize the calculation. The network can be visualized directly in the browser or in Cytoscape. Alternatively, the RING-Viz script for Pymol allows visualizing the interactions at atomic level in the structure. The web server and RING-Viz, together with an extensive help and tutorial, are available from URL: http://protein.bio.unipd.it/ring. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Networked buffering: a basic mechanism for distributed robustness in complex adaptive systems.

PubMed

Whitacre, James M; Bender, Axel

2010-06-15

A generic mechanism--networked buffering--is proposed for the generation of robust traits in complex systems. It requires two basic conditions to be satisfied: 1) agents are versatile enough to perform more than one single functional role within a system and 2) agents are degenerate, i.e. there exists partial overlap in the functional capabilities of agents. Given these prerequisites, degenerate systems can readily produce a distributed systemic response to local perturbations. Reciprocally, excess resources related to a single function can indirectly support multiple unrelated functions within a degenerate system. In models of genome:proteome mappings for which localized decision-making and modularity of genetic functions are assumed, we verify that such distributed compensatory effects cause enhanced robustness of system traits. The conditions needed for networked buffering to occur are neither demanding nor rare, supporting the conjecture that degeneracy may fundamentally underpin distributed robustness within several biotic and abiotic systems. For instance, networked buffering offers new insights into systems engineering and planning activities that occur under high uncertainty. It may also help explain recent developments in understanding the origins of resilience within complex ecosystems.

The number and type of food retailers surrounding schools and their association with lunchtime eating behaviours in students.

PubMed

Seliske, Laura; Pickett, William; Rosu, Andrei; Janssen, Ian

2013-02-07

The primary study objective was to examine whether the presence of food retailers surrounding schools was associated with students' lunchtime eating behaviours. The secondary objective was to determine whether measures of the food retail environment around schools captured using road network or circular buffers were more strongly related to eating behaviours while at school. Grade 9 and 10 students (N=6,971) who participated in the 2009/10 Canadian Health Behaviour in School Aged Children Survey were included in this study. The outcome was determined by students' self-reports of where they typically ate their lunch during school days. Circular and road network-based buffers were created for a 1 km distance surrounding 158 schools participating in the HBSC. The addresses of fast food restaurants, convenience stores and coffee/donut shops were mapped within the buffers. Multilevel logistic regression was used to determine whether there was a relationship between the presence of food retailers near schools and students regularly eating their lunch at a fast food restaurant, snack-bar or café. The Akaike Information Criteria (AIC) value, a measure of goodness-of-fit, was used to determine the optimal buffer type. For the 1 km circular buffers, students with 1-2 (OR= 1.10, 95% CI: 0.57-2.11), 3-4 (OR=1.45, 95% CI: 0.75-2.82) and ≥5 nearby food retailers (OR=2.94, 95% CI: 1.71-5.09) were more likely to eat lunch at a food retailer compared to students with no nearby food retailers. The relationships were slightly stronger when assessed via 1 km road network buffers, with a greater likelihood of eating at a food retailer for 1-2 (OR=1.20, 95% CI:0.74-1.95), 3-4 (OR=3.19, 95% CI: 1.66-6.13) and ≥5 nearby food retailers (OR=3.54, 95% CI: 2.08-6.02). Road network buffers appeared to provide a better measure of the food retail environment, as indicated by a lower AIC value (3332 vs. 3346). There was a strong relationship between the presence of food retailers near schools and students' lunchtime eating behaviours. Results from the goodness of fit analysis suggests that road network buffers provide a more optimal measure of school neighbourhood food environments relative to circular buffers.

Low-noise sub-harmonic injection locked multiloop ring oscillator

NASA Astrophysics Data System (ADS)

Weilin, Xu; Di, Wu; Xueming, Wei; Baolin, Wei; Jihai, Duan; Fadi, Gui

2016-09-01

A three-stage differential voltage-controlled ring oscillator is presented for wide-tuning and low-phase noise requirement of clock and data recovery circuit in ultra wideband (UWB) wireless body area network. To improve the performance of phase noise of delay cell with coarse and fine frequency tuning, injection locked technology together with pseudo differential architecture are adopted. In addition, a multiloop is employed for frequency boosting. Two RVCOs, the standard RVCO without the IL block and the proposed IL RVCO, were fabricated in SMIC 0.18 μm 1P6M Salicide CMOS process. The proposed IL RVCO exhibits a measured phase noise of -112.37 dBc/Hz at 1 MHz offset from the center frequency of 1 GHz, while dissipating a current of 8 mA excluding the buffer from a 1.8-V supply voltage. It shows a 16.07 dB phase noise improvement at 1 MHz offset compared to the standard topology. Project supported by the National Natural Science Foundation of China (No. 61264001), the Guangxi Natural Science Foundation (Nos. 2013GXNSFAA019333, 2015GXNSFAA139301, 2014GXNSFAA118386), the Graduate Education Innovation Program of GUET (No. GDYCSZ201457), the Project of Guangxi Education Department (No. LD14066B) and the High-Level-Innovation Team and Outstanding Scholar Project of Guangxi Higher Education Institutes.

Tabun scavengers based on hydroxamic acid containing cyclodextrins.

PubMed

Brandhuber, Florian; Zengerle, Michael; Porwol, Luzian; Bierwisch, Anne; Koller, Marianne; Reiter, Georg; Worek, Franz; Kubik, Stefan

2013-04-28

Arrangement of several hydroxamic acid-derived substituents along the cavity of a cyclodextrin ring leads to compounds that detoxify tabun in TRIS-HCl buffer at physiological pH and 37.0 °C with half-times as low as 3 min.

Real-time Data Access to First Responders: A VORB application

NASA Astrophysics Data System (ADS)

Lu, S.; Kim, J. B.; Bryant, P.; Foley, S.; Vernon, F.; Rajasekar, A.; Meier, S.

2006-12-01

Getting information to first responders is not an easy task. The sensors that provide the information are diverse in formats and come from many disciplines. They are also distributed by location, transmit data at different frequencies and are managed and owned by autonomous administrative entities. Pulling such types of data in real-time, needs a very robust sensor network with reliable data transport and buffering capabilities. Moreover, the system should be extensible and scalable in numbers and sensor types. ROADNet is a real- time sensor network project at UCSD gathering diverse environmental data in real-time or near-real-time. VORB (Virtual Object Ring Buffer) is the middleware used in ROADNet offering simple, uniform and scalable real-time data management for discovering (through metadata), accessing and archiving real-time data and data streams. Recent development in VORB, a web API, has offered quick and simple real-time data integration with web applications. In this poster, we discuss one application developed as part of ROADNet. SMER (Santa Margarita Ecological Reserve) is located in interior Southern California, a region prone to catastrophic wildfires each summer and fall. To provide data during emergencies, we have applied the VORB framework to develop a web-based application for providing access to diverse sensor data including weather data, heat sensor information, and images from cameras. Wildfire fighters have access to real-time data about weather and heat conditions in the area and view pictures taken from cameras at multiple points in the Reserve to pinpoint problem areas. Moreover, they can browse archived images and sensor data from earlier times to provide a comparison framework. To show scalability of the system, we have expanded the sensor network under consideration through other areas in Southern California including sensors accessible by Los Angeles County Fire Department (LACOFD) and those available through the High Performance Wireless Research and Education Network (HPWREN). The poster will discuss the system architecture and components, the types of sensor being used and usage scenarios. The system is currently operational through the SMER web-site.

Assembly of Modified Ferritin Proteins on Carbon Nanotubes and its Electrocatalytic Activity for Oxygen Reduction

NASA Technical Reports Server (NTRS)

Kim, Jae-Woo; Lillehei, Peter T.; Park, Cheol

2012-01-01

Highly effective dispersions of carbon nanotubes (CNTs) can be made using a commercially available buffer solution. Buffer solutions of 3-(N-morpholino)-propanesulfonic acid (MOPS), which consists of a cyclic ring with nitrogen and oxygen heteroatoms, a charged group, and an alkyl chain greatly enhance the dispersibility and stability of CNTs in aqueous solutions. Additionally, the ability of biomolecules, especially cationized Pt-cored ferritins, to adhere onto the well-dispersed CNTs in the aqueous buffer solution is also improved. This was accomplished without the use of surfactant molecules, which are detrimental to the electrical, mechanical, and other physical properties of the resulting products. The assembled Pt-cored ferritin proteins on the CNTs were used as an electrocatalyst for oxygen reduction

Partition coefficients of some purine derivatives and its application to pharmacokinetics.

PubMed

Chrzanowska, M; Sobiak, J; Kuehn, M; Dorawa, E; Hermann, T

2009-12-01

Metazathioprine (MAZA), a methylated derivative of azathioprine (AZA), demonstrated the greatest values of apparent and specific partition coefficients in n-octanol/phosphate buffer at pH 5.7 and pH 7.4 among purine derivatives such as 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) and AZA. Introduction of a methyl group into the imidazole ring of AZA increases lipophilic properties of MAZA compared to AZA. Mass balance of purine derivatives in n-octanol and in phosphate buffer indicated their chemical stability in those media.

Increased tree-ring network density reveals more precise estimations of sub-regional hydroclimate variability and climate dynamics in the Midwest, USA

NASA Astrophysics Data System (ADS)

Maxwell, Justin T.; Harley, Grant L.

2017-08-01

Understanding the historic variability in the hydroclimate provides important information on possible extreme dry or wet periods that in turn inform water management plans. Tree rings have long provided historical context of hydroclimate variability of the U.S. However, the tree-ring network used to create these countrywide gridded reconstructions is sparse in certain locations, such as the Midwest. Here, we increase ( n = 20) the spatial resolution of the tree-ring network in southern Indiana and compare a summer (June-August) Palmer Drought Severity Index (PDSI) reconstruction to existing gridded reconstructions of PDSI for this region. We find both droughts and pluvials that were previously unknown that rival the most intense PDSI values during the instrumental period. Additionally, historical drought occurred in Indiana that eclipsed instrumental conditions with regard to severity and duration. During the period 1962-2004 CE, we find that teleconnections of drought conditions through the Atlantic Meridional Overturning Circulation have a strong influence ( r = -0.60, p < 0.01) on secondary tree growth in this region for the late spring-early summer season. These findings highlight the importance of continuing to increase the spatial resolution of the tree-ring network used to infer past climate dynamics to capture the sub-regional spatial variability. Increasing the spatial resolution of the tree-ring network for a given region can better identify sub-regional variability, improve the accuracy of regional tree-ring PDSI reconstructions, and provide better information for climatic teleconnections.

A novel survivable architecture for hybrid WDM/TDM passive optical networks

NASA Astrophysics Data System (ADS)

Qiu, Yang; Chan, Chun-Kit

2014-02-01

A novel tree-ring survivable architecture, which consists of an organization of a wavelength-division-multiplexing (WDM) tree from optical line terminal (OLT) to remote nodes (RNs) and a time division multiplexing (TDM) ring in each RN, is proposed for hybrid WDM/TDM passive optical networks. By utilizing the cyclic property of arrayed waveguide gratings (AWGs) and the single-ring topology among a group of optical network units (ONUs) in the remote node, not only the feeder and distribution fibers, but also any fiber failures in the RN rings are protected simultaneously. Five-Gbit/s transmissions under both normal working and protection modes were experimentally demonstrated and a traffic restoration time was successfully measured.

Essential SpaceWire Hardware Capabilities for a Robust Network

NASA Technical Reports Server (NTRS)

Birmingham, Michael; Krimchansky, Alexander; Anderson, William; Lombardi, Matthew

2016-01-01

The Geostationary Operational Environmental Satellite R-Series Program (GOES-R) mission is a joint program between National Oceanic & Atmospheric Administration (NOAA) and National Aeronautics & Space Administration (NASA) Goddard Space Flight Center (GSFC). GOES-R project selected SpaceWire as the best solution to satisfy the desire for simple and flexible instrument to spacecraft command and telemetry communications. GOES-R development and integration is complete and the observatory is scheduled for launch October 2016. The spacecraft design was required to support redundant SpaceWire links for each instrument side, as well as to route the fewest number of connections through a Slip Ring Assembly necessary to support Solar pointing instruments. The final design utilized two different router designs. The SpaceWire standard alone does not ensure the most practical or reliable network. On GOES-R a few key hardware capabilities were identified that merit serious consideration for future designs. Primarily these capabilities address persistent port stalls and the prevention of receive buffer overflows. Workarounds were necessary to overcome shortcomings that could be avoided in future designs if they utilize the capabilities, discussed in this paper, above and beyond the requirements of the SpaceWire standard.

The number and type of food retailers surrounding schools and their association with lunchtime eating behaviours in students

PubMed Central

2013-01-01

Background The primary study objective was to examine whether the presence of food retailers surrounding schools was associated with students’ lunchtime eating behaviours. The secondary objective was to determine whether measures of the food retail environment around schools captured using road network or circular buffers were more strongly related to eating behaviours while at school. Methods Grade 9 and 10 students (N=6,971) who participated in the 2009/10 Canadian Health Behaviour in School Aged Children Survey were included in this study. The outcome was determined by students’ self-reports of where they typically ate their lunch during school days. Circular and road network-based buffers were created for a 1 km distance surrounding 158 schools participating in the HBSC. The addresses of fast food restaurants, convenience stores and coffee/donut shops were mapped within the buffers. Multilevel logistic regression was used to determine whether there was a relationship between the presence of food retailers near schools and students regularly eating their lunch at a fast food restaurant, snack-bar or café. The Akaike Information Criteria (AIC) value, a measure of goodness-of-fit, was used to determine the optimal buffer type. Results For the 1 km circular buffers, students with 1–2 (OR= 1.10, 95% CI: 0.57-2.11), 3–4 (OR=1.45, 95% CI: 0.75-2.82) and ≥5 nearby food retailers (OR=2.94, 95% CI: 1.71-5.09) were more likely to eat lunch at a food retailer compared to students with no nearby food retailers. The relationships were slightly stronger when assessed via 1 km road network buffers, with a greater likelihood of eating at a food retailer for 1–2 (OR=1.20, 95% CI:0.74-1.95), 3–4 (OR=3.19, 95% CI: 1.66-6.13) and ≥5 nearby food retailers (OR=3.54, 95% CI: 2.08-6.02). Road network buffers appeared to provide a better measure of the food retail environment, as indicated by a lower AIC value (3332 vs. 3346). Conclusions There was a strong relationship between the presence of food retailers near schools and students’ lunchtime eating behaviours. Results from the goodness of fit analysis suggests that road network buffers provide a more optimal measure of school neighbourhood food environments relative to circular buffers. PMID:23391296

Photonic integrated circuit optical buffer for packet-switched networks.

PubMed

Burmeister, Emily F; Mack, John P; Poulsen, Henrik N; Masanović, Milan L; Stamenić, Biljana; Blumenthal, Daniel J; Bowers, John E

2009-04-13

A chip-scale optical buffer performs autonomous contention resolution for 40-byte packets with 99% packet recovery. The buffer consists of a fast, InP-based 2 x 2 optical switch and a silica-on-silicon low loss delay loop. The buffer is demonstrated in recirculating operation, but may be reconfigured in feed-forward operation for longer packet lengths. The recirculating buffer provides packet storage in integer multiples of the delay length of 12.86 ns up to 64.3 ns with 98% packet recovery. The buffer is used to resolve contention between two 40 Gb/s packet streams using multiple photonic chip optical buffers.

Multiple-Ring Digital Communication Network

NASA Technical Reports Server (NTRS)

Kirkham, Harold

1992-01-01

Optical-fiber digital communication network to support data-acquisition and control functions of electric-power-distribution networks. Optical-fiber links of communication network follow power-distribution routes. Since fiber crosses open power switches, communication network includes multiple interconnected loops with occasional spurs. At each intersection node is needed. Nodes of communication network include power-distribution substations and power-controlling units. In addition to serving data acquisition and control functions, each node acts as repeater, passing on messages to next node(s). Multiple-ring communication network operates on new AbNET protocol and features fiber-optic communication.

A dynamic routing strategy with limited buffer on scale-free network

NASA Astrophysics Data System (ADS)

Wang, Yufei; Liu, Feng

2016-04-01

In this paper, we propose an integrated routing strategy based on global static topology information and local dynamic data packet queue lengths to improve the transmission efficiency of scale-free networks. The proposed routing strategy is a combination of a global static routing strategy (based on the shortest path algorithm) and local dynamic queue length management, in which, instead of using an infinite buffer, the queue length of each node i in the proposed routing strategy is limited by a critical queue length Qic. When the network traffic is lower and the queue length of each node i is shorter than its critical queue length Qic, it forwards packets according to the global routing table. With increasing network traffic, when the buffers of the nodes with higher degree are full, they do not receive packets due to their limited buffers and the packets have to be delivered to the nodes with lower degree. The global static routing strategy can shorten the transmission time that it takes a packet to reach its destination, and the local limited queue length can balance the network traffic. The optimal critical queue lengths of nodes have been analysed. Simulation results show that the proposed routing strategy can get better performance than that of the global static strategy based on topology, and almost the same performance as that of the global dynamic routing strategy with less complexity.

Common data buffer

NASA Technical Reports Server (NTRS)

Byrne, F.

1981-01-01

Time-shared interface speeds data processing in distributed computer network. Two-level high-speed scanning approach routes information to buffer, portion of which is reserved for series of "first-in, first-out" memory stacks. Buffer address structure and memory are protected from noise or failed components by error correcting code. System is applicable to any computer or processing language.

A tangent-ring optical TWDM-MAN enabling three-level transregional reconfigurations and shared protections by multipoint distributed control

NASA Astrophysics Data System (ADS)

Gou, Kaiyu; Gan, Chaoqin; Zhang, Xiaoyu; Zhang, Yuchao

2018-03-01

An optical time-and-wavelength-division-multiplexing metro-access network (TWDM-MAN) is proposed and demonstrated in this paper. By the reuse of tangent-ring optical distribution network and the design of distributed control mechanism, ONUs needing to communicate with each other can be flexibly accessed to successfully make up three kinds of reconfigurable networks. By the nature advantage of ring topology in protection, three-level comprehensive protections covering both feeder and distribution fibers are also achieved. Besides, a distributed wavelength allocation (DWA) is designed to support efficient parallel upstream transmission. The analyses including capacity, congestion and transmission simulation show that this network has a great performance.

Traffic shaping and scheduling for OBS-based IP/WDM backbones

NASA Astrophysics Data System (ADS)

Elhaddad, Mahmoud S.; Melhem, Rami G.; Znati, Taieb; Basak, Debashis

2003-10-01

We introduce Proactive Reservation-based Switching (PRS) -- a switching architecture for IP/WDM networks based on Labeled Optical Burst Switching. PRS achieves packet delay and loss performance comparable to that of packet-switched networks, without requiring large buffering capacity, or burst scheduling across a large number of wavelengths at the core routers. PRS combines proactive channel reservation with periodic shaping of ingress-egress traffic aggregates to hide the offset latency and approximate the utilization/buffering characteristics of discrete-time queues with periodic arrival streams. A channel scheduling algorithm imposes constraints on burst departure times to ensure efficient utilization of wavelength channels and to maintain the distance between consecutive bursts through the network. Results obtained from simulation using TCP traffic over carefully designed topologies indicate that PRS consistently achieves channel utilization above 90% with modest buffering requirements.

Some dynamic resource allocation problems in wireless networks

NASA Astrophysics Data System (ADS)

Berry, Randall

2001-07-01

We consider dynamic resource allocation problems that arise in wireless networking. Specifically transmission scheduling problems are studied in cases where a user can dynamically allocate communication resources such as transmission rate and power based on current channel knowledge as well as traffic variations. We assume that arriving data is stored in a transmission buffer, and investigate the trade-off between average transmission power and average buffer delay. A general characterization of this trade-off is given and the behavior of this trade-off in the regime of asymptotically large buffer delays is explored. An extension to a more general utility based quality of service definition is also discussed.

Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments.

PubMed

Ayub, Qaisar; Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

2018-01-01

Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio.

Priority Queue Based Reactive Buffer Management Policy for Delay Tolerant Network under City Based Environments

PubMed Central

Ngadi, Asri; Rashid, Sulma; Habib, Hafiz Adnan

2018-01-01

Delay Tolerant Network (DTN) multi-copy routing protocols are privileged to create and transmit multiple copies of each message that causes congestion and some messages are dropped. This process is known as reactive drop because messages were dropped re-actively to overcome buffer overflows. The existing reactive buffer management policies apply a single metric to drop source, relay and destine messages. Hereby, selection to drop a message is dubious because each message as source, relay or destine may have consumed dissimilar magnitude of network resources. Similarly, DTN has included time to live (ttl) parameter which defines lifetime of message. Hence, when ttl expires then message is automatically destroyed from relay nodes. However, time-to-live (ttl) is not applicable on messages reached at their destinations. Moreover, nodes keep replicating messages till ttl expires even-though large number of messages has already been dispersed. In this paper, we have proposed Priority Queue Based Reactive Buffer Management Policy (PQB-R) for DTN under City Based Environments. The PQB-R classifies buffered messages into source, relay and destine queues. Moreover, separate drop metric has been applied on individual queue. The experiment results prove that proposed PQB-R has reduced number of messages transmissions, message drop and increases delivery ratio. PMID:29438438

Photophysical investigations of squaraine and cyanine dyes and their interaction with bovine serum albumin

NASA Astrophysics Data System (ADS)

Saikiran, M.; Sato, D.; Pandey, S. S.; Kato, T.

2016-04-01

A model far-red sensitive symmetrical squaraine dye (SQ-3) and unsymmetrical near infra-red sensitive cyanine dye (UCD-1) bearing direct-COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations including their interaction with bovine serum albumin (BSA) as a model protein in phosphate buffer solution (PBS). Both of the dyes exhibit strong interaction with BSA in phosphate buffer with high apparent binding constant. A judicious tuning of hydrophobic main backbone with reactive functionality for associative interaction with active site of BSA has been found to be necessary for BSA detection in PBS.

Dynamically-allocated multi-queue buffers for VLSI communication switches

NASA Technical Reports Server (NTRS)

Tamir, Yuval; Frazier, Gregory L.

1992-01-01

Several buffer structures are discussed and compared in terms of implementation complexity, interswitch handshaking requirements, and their ability to deal with variations in traffic patterns and message lengths. A new design of buffers is presented that provide non-FIFO message handling and efficient storage allocation for variable size packets using linked lists managed by a simple on-chip controller. The new buffer design is evaluated by comparing it to several alternative designs in the context of a multistage interconnection network. The present modeling and simulations show that the new buffer outperforms alternative buffers and can thus be used to improve the performance of a wide variety of systems currently using less efficient buffers.

Defining essential elements and genetic interactions of the yeast Lsm2-8 ring and demonstration that essentiality of Lsm2-8 is bypassed via overexpression of U6 snRNA or the U6 snRNP subunit Prp24.

PubMed

Roth, Allen J; Shuman, Stewart; Schwer, Beate

2018-06-01

A seven-subunit Lsm2-8 protein ring assembles on the U-rich 3' end of the U6 snRNA. A structure-guided mutational analysis of the Saccharomyces cerevisiae Lsm2-8 ring affords new insights to structure-function relations and genetic interactions of the Lsm subunits. Alanine scanning of 39 amino acids comprising the RNA-binding sites or intersubunit interfaces of Lsm2, Lsm3, Lsm4, Lsm5, and Lsm8 identified only one instance of lethality (Lsm3-R69A) and one severe growth defect (Lsm2-R63A), both involving amino acids that bind the 3'-terminal UUU trinucleotide. All other Ala mutations were benign with respect to vegetative growth. Tests of 235 pairwise combinations of benign Lsm mutants identified six instances of inter-Lsm synthetic lethality and 45 cases of nonlethal synthetic growth defects. Thus, Lsm2-8 ring function is buffered by a network of internal genetic redundancies. A salient finding was that otherwise lethal single-gene deletions lsm2 Δ, lsm3 Δ, lsm4 Δ, lsm5 , and lsm8 Δ were rescued by overexpression of U6 snRNA from a high-copy plasmid. Moreover, U6 overexpression rescued myriad lsm Δ lsm Δ double-deletions and lsm Δ lsm Δ lsm Δ triple-deletions. We find that U6 overexpression also rescues a lethal deletion of the U6 snRNP protein subunit Prp24 and that Prp24 overexpression bypasses the essentiality of the U6-associated Lsm subunits. Our results indicate that abetting U6 snRNA is the only essential function of the yeast Lsm2-8 proteins. © 2018 Roth et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

Synchronization properties of network motifs: Influence of coupling delay and symmetry

NASA Astrophysics Data System (ADS)

D'Huys, O.; Vicente, R.; Erneux, T.; Danckaert, J.; Fischer, I.

2008-09-01

We investigate the effect of coupling delays on the synchronization properties of several network motifs. In particular, we analyze the synchronization patterns of unidirectionally coupled rings, bidirectionally coupled rings, and open chains of Kuramoto oscillators. Our approach includes an analytical and semianalytical study of the existence and stability of different in-phase and out-of-phase periodic solutions, complemented by numerical simulations. The delay is found to act differently on networks possessing different symmetries. While for the unidirectionally coupled ring the coupling delay is mainly observed to induce multistability, its effect on bidirectionally coupled rings is to enhance the most symmetric solution. We also study the influence of feedback and conclude that it also promotes the in-phase solution of the coupled oscillators. We finally discuss the relation between our theoretical results on delay-coupled Kuramoto oscillators and the synchronization properties of networks consisting of real-world delay-coupled oscillators, such as semiconductor laser arrays and neuronal circuits.

Effects of riparian buffer width on wood loading in headwater streams after repeated forest thinning

Treesearch

Julia I. Burton; Deanna H. Olson; Klaus J. Puettmann

2016-01-01

Forested riparian buffer zones are used in conjunction with upland forest management, in part, to provide for the recruitment for large wood to streams. Small headwater streams account for the majority of stream networks in many forested regions. Yet, our understanding of how riparian buffer width influences wood dynamics in headwater streams is relatively less...

A Network Pump

DTIC Science & Technology

1996-05-01

introduced as shown in Fig. 3. Pump ~ y { ~ ~ ~ = ~ messages ACK buffer Fig. 3. The Basic Pump The basic Pump [6] places a buffer (size n ) between...exponential distribution with mean x. Define Q = fY(MAll - T,) + k . ( N - Fair size) where N is the number of messages in buffer, at the time the...message is placed in buffer,,, and k . ( N - Fair size) is a feedback term. Both k and Fair size can be chosen by a sys- tem designer. Note that the moving

Chip-set for quality of service support in passive optical networks

NASA Astrophysics Data System (ADS)

Ringoot, Edwin; Hoebeke, Rudy; Slabbinck, B. Hans; Verhaert, Michel

1998-10-01

In this paper the design of a chip-set for QoS provisioning in ATM-based Passive Optical Networks is discussed. The implementation of a general-purpose switch chip on the Optical Network Unit is presented, with focus on the design of the cell scheduling and buffer management logic. The cell scheduling logic supports `colored' grants, priority jumping and weighted round-robin scheduling. The switch chip offers powerful buffer management capabilities enabling the efficient support of GFR and UBR services. Multicast forwarding is also supported. In addition, the architecture of a MAC controller chip developed for a SuperPON access network is introduced. In particular, the permit scheduling logic and its implementation on the Optical Line Termination will be discussed. The chip-set enables the efficient support of services with different service requirements on the SuperPON. The permit scheduling logic built into the MAC controller chip in combination with the cell scheduling and buffer management capabilities of the switch chip can be used by network operators to offer guaranteed service performance to delay sensitive services, and to efficiently and fairly distribute any spare capacity to delay insensitive services.

Utilization of Concurrent Buffers to Facilitate Seamless Data Transition in Tactical Cellular Communications

DTIC Science & Technology

2015-09-01

INTENTIONALLY LEFT BLANK xiii LIST OF ACRONYMS AND ABBREVIATIONS 2G 2nd Generation 3G 3rd Generation 3GPP 3rd Generation Partnership Project 4G 4th...System (UMTS) is the standard that governs 3rd Generation ( 3G ) migration of Global Services for Mobile (GSM) networks. It defines packet-based...network may assist or mitigate. 14. SUBJECT TERMS IEEE, 802.21, Media Independent Handover, mobile , communications, cyber, tactical, buffer, cellular

Pyrolytic sugars from cellulosic biomass.

PubMed

Kuzhiyil, Najeeb; Dalluge, Dustin; Bai, Xianglan; Kim, Kwang Ho; Brown, Robert C

2012-11-01

Depolymerization of cellulose offers the prospect of inexpensive sugars from biomass. Breaking the glycosidic bonds of cellulose to liberate glucose has usually been pursued by acid or enzymatic hydrolysis although a purely thermal depolymerization route to sugars is also possible. Fast pyrolysis of pure cellulose yields primarily the anhydrosugar levoglucosan (LG) whereas the presence of naturally occurring alkali and alkaline earth metals (AAEMs) in biomass strongly catalyzes ring-breaking reactions that favor formation of light oxygenates. Here, we show a method of significantly increasing the yield of sugars from biomass by purely thermal means through infusion of certain mineral acids (phosphoric and sulfuric acid) into the biomass to convert the AAEMs into thermally stable salts (particularly potassium sulfates and phosphates). These salts not only passivate AAEMs that normally catalyze fragmentation of pyranose rings, but also buffer the system at pH levels that favor glycosidic bond breakage. It appears that AAEM passivation contributes to 80 % of the enhancement in LG yield while the buffering effect of the acid salts contributes to the balance of the enhancement. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of oil consumption in cylinder of diesel engine for optimization of piston rings

NASA Astrophysics Data System (ADS)

Zhang, Junhong; Zhang, Guichang; He, Zhenpeng; Lin, Jiewei; Liu, Hai

2013-01-01

The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil. Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method, however they are very costly. Therefore, it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method. Firstly, four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine. Then, the factors that affect the lubricating oil consumption such as working conditions, the second ring closed gap, the elastic force of the piston rings are also investigated for the four modes. The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface. Besides, there are three other findings: (1) The oil evaporation from the liner is determined by the working condition of an engine; (2) The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by; (3) With the increase of the elastic force of the ring, both the left oil film thickness and the oil throw-off at the top ring decrease. The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases. A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory, and then the model is trained and validated. The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%, which is acceptable for normal engineering applications. The oil consumption is also measured experimentally. The relative errors of the calculated and experimental values are less than 10%, verifying the validity of the simulation results. Applying the established simulation model and the validated BP network model is able to generate numerical results with sufficient accuracy, which significantly reduces experimental work and provides guidance for the optimal design of the piston rings diesel engines.

Queueing models for token and slotted ring networks. Thesis

NASA Technical Reports Server (NTRS)

Peden, Jeffery H.

1990-01-01

Currently the end-to-end delay characteristics of very high speed local area networks are not well understood. The transmission speed of computer networks is increasing, and local area networks especially are finding increasing use in real time systems. Ring networks operation is generally well understood for both token rings and slotted rings. There is, however, a severe lack of queueing models for high layer operation. There are several factors which contribute to the processing delay of a packet, as opposed to the transmission delay, e.g., packet priority, its length, the user load, the processor load, the use of priority preemption, the use of preemption at packet reception, the number of processors, the number of protocol processing layers, the speed of each processor, and queue length limitations. Currently existing medium access queueing models are extended by adding modeling techniques which will handle exhaustive limited service both with and without priority traffic, and modeling capabilities are extended into the upper layers of the OSI model. Some of the model are parameterized solution methods, since it is shown that certain models do not exist as parameterized solutions, but rather as solution methods.

Energy efficiency evaluation of tree-topology 10 gigabit ethernet passive optical network and ring-topology time- and wavelength-division-multiplexed passive optical network

NASA Astrophysics Data System (ADS)

Song, Jingjing; Yang, Chuanchuan; Zhang, Qingxiang; Ma, Zhuang; Huang, Xingang; Geng, Dan; Wang, Ziyu

2015-09-01

Higher capacity and larger scales have always been the top targets for the evolution of optical access networks, driven by the ever-increasing demand from the end users. One thing that started to attract wide attention not long ago, but with at least equal importance as capacity and scale, is energy efficiency, a metric essential nowadays as human beings are confronted with severe environmental issues like global warming, air pollution, and so on. Here, different from the conventional energy consumption analysis of tree-topology networks, we propose an effective energy consumption calculation method to compare the energy efficiency of the tree-topology 10 gigabit ethernet passive optical network (10G-EPON) and ring-topology time- and wavelength-division-multiplexed passive optical network (TWDM-PON), two experimental networks deployed in China. Numerical results show that the ring-topology TWDM-PON networks with 2, 4, 8, and 16 wavelengths are more energy efficient than the tree-topology 10G-EPON, although 10G-EPON consumes less energy. Also, TWDM-PON with four wavelengths is the most energy-efficient network candidate and saves 58.7% more energy than 10G-EPON when fully loaded.

The RING domain of the scaffold protein Ste5 adopts a molten globular character with high thermal and chemical stability.

PubMed

Walczak, Michal J; Samatanga, Brighton; van Drogen, Frank; Peter, Matthias; Jelesarov, Ilian; Wider, Gerhard

2014-01-27

Ste5 is a scaffold protein that controls the pheromone response of the MAP-kinase cascade in yeast cells. Upon pheromone stimulation, Ste5 (through its RING-H2 domain) interacts with the β and γ subunits of an activated heterodimeric G protein and promotes activation of the MAP-kinase cascade. With structural and biophysical studies, we show that the Ste5 RING-H2 domain exists as a molten globule under native buffer conditions, in yeast extracts, and even in denaturing conditions containing urea (7 M). Furthermore, it exhibits high thermal stability in native conditions. Binding of the Ste5 RING-H2 domain to the physiological Gβ/γ (Ste4/Ste18) ligand is accompanied by a conformational transition into a better folded, more globular structure. This study reveals novel insights into the folding mechanism and recruitment of binding partners by the Ste5 RING-H2 domain. We speculate that many RING domains may share a similar mechanism of substrate recognition and molten-globule-like character. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Social buffering and contact transmission: network connections have beneficial and detrimental effects on Shigella infection risk among captive rhesus macaques

PubMed Central

Beisner, Brianne; Vandeleest, Jessica; Atwill, Edward; McCowan, Brenda

2016-01-01

In social animals, group living may impact the risk of infectious disease acquisition in two ways. On the one hand, social connectedness puts individuals at greater risk or susceptibility for acquiring enteric pathogens via contact-mediated transmission. Yet conversely, in strongly bonded societies like humans and some nonhuman primates, having close connections and strong social ties of support can also socially buffer individuals against susceptibility or transmissibility of infectious agents. Using social network analyses, we assessed the potentially competing roles of contact-mediated transmission and social buffering on the risk of infection from an enteric bacterial pathogen (Shigella flexneri) among captive groups of rhesus macaques (Macaca mulatta). Our results indicate that, within two macaque groups, individuals possessing more direct and especially indirect connections in their grooming and huddling social networks were less susceptible to infection. These results are in sharp contrast to several previous studies that indicate that increased (direct) contact-mediated transmission facilitates infectious disease transmission, including our own findings in a third macaque group in which individuals central in their huddling network and/or which initiated more fights were more likely to be infected. In summary, our findings reveal that an individual’s social connections may increase or decrease its chances of acquiring infectious agents. They extend the applicability of the social buffering hypothesis, beyond just stress and immune-function-related health benefits, to the additional health outcome of infectious disease resistance. Finally, we speculate that the circumstances under which social buffering versus contact-mediated transmission may occur could depend on multiple factors, such as living condition, pathogen-specific transmission routes, and/or an overall social context such as a group’s social stability. PMID:27812426

Evaluating the diffusion coefficient of dopamine at the cell surface during amperometric detection: disk vs ring microelectrodes.

PubMed

Trouillon, Raphaël; Lin, Yuqing; Mellander, Lisa J; Keighron, Jacqueline D; Ewing, Andrew G

2013-07-02

During exocytosis, small quantities of neurotransmitters are released by the cell. These neurotransmitters can be detected quantitatively using electrochemical methods, principally with disk carbon fiber microelectrode amperometry. An exocytotic event then results in the recording of a current peak whose characteristic features are directly related to the mechanisms of exocytosis. We have compared two exocytotic peak populations obtained from PC12 cells with a disk carbon fiber microelectrode and with a pyrolyzed carbon ring microelectrode array, with a 500 nm ring thickness. The specific shape of the ring electrode allows for precise analysis of diffusion processes at the vicinity of the cell membrane. Peaks obtained with a ring microelectrode array show a distorted average shape, owing to increased diffusion pathways. This result has been used to evaluate the diffusion coefficient of dopamine at the surface of a cell, which is up to an order of magnitude smaller than that measured in free buffer. The lower rate of diffusion is discussed as resulting from interactions with the glycocalyx.

Intelligent deflection routing in buffer-less networks.

PubMed

Haeri, Soroush; Trajković, Ljiljana

2015-02-01

Deflection routing is employed to ameliorate packet loss caused by contention in buffer-less architectures such as optical burst-switched networks. The main goal of deflection routing is to successfully deflect a packet based only on a limited knowledge that network nodes possess about their environment. In this paper, we present a framework that introduces intelligence to deflection routing (iDef). iDef decouples the design of the signaling infrastructure from the underlying learning algorithm. It consists of a signaling and a decision-making module. Signaling module implements a feedback management protocol while the decision-making module implements a reinforcement learning algorithm. We also propose several learning-based deflection routing protocols, implement them in iDef using the ns-3 network simulator, and compare their performance.

Energy-efficient rings mechanism for greening multisegment fiber-wireless access networks

NASA Astrophysics Data System (ADS)

Gong, Xiaoxue; Guo, Lei; Hou, Weigang; Zhang, Lincong

2013-07-01

Through integrating advantages of optical and wireless communications, the Fiber-Wireless (FiWi) has become a promising solution for the "last-mile" broadband access. In particular, greening FiWi has attained extensive attention, because the access network is a main energy contributor in the whole infrastructure. However, prior solutions of greening FiWi shut down or sleep unused/minimally used optical network units for a single segment, where we deploy only one optical linear terminal. We propose a green mechanism referred to as energy-efficient ring (EER) for multisegment FiWi access networks. We utilize an integer linear programming model and a generic algorithm to generate clusters, each having the shortest distance of fully connected segments of its own. Leveraging the backtracking method for each cluster, we then connect segments through fiber links, and the shortest distance fiber ring is constructed. Finally, we sleep low load segments and forward affected traffic to other active segments on the same fiber ring by our sleeping scheme. Experimental results show that our EER mechanism significantly reduces the energy consumption at the slightly additional cost of deploying fiber links.

Real-Time Continuous Response Spectra Exceedance Calculation Displayed in a Web-Browser Enables Rapid and Robust Damage Evaluation by First Responders

NASA Astrophysics Data System (ADS)

Franke, M.; Skolnik, D. A.; Harvey, D.; Lindquist, K.

2014-12-01

A novel and robust approach is presented that provides near real-time earthquake alarms for critical structures at distributed locations and large facilities using real-time estimation of response spectra obtained from near free-field motions. Influential studies dating back to the 1980s identified spectral response acceleration as a key ground motion characteristic that correlates well with observed damage in structures. Thus, monitoring and reporting on exceedance of spectra-based thresholds are useful tools for assessing the potential for damage to facilities or multi-structure campuses based on input ground motions only. With as little as one strong-motion station per site, this scalable approach can provide rapid alarms on the damage status of remote towns, critical infrastructure (e.g., hospitals, schools) and points of interests (e.g., bridges) for a very large number of locations enabling better rapid decision making during critical and difficult immediate post-earthquake response actions. Details on the novel approach are presented along with an example implementation for a large energy company. Real-time calculation of PSA exceedance and alarm dissemination are enabled with Bighorn, an extension module based on the Antelope software package that combines real-time spectral monitoring and alarm capabilities with a robust built-in web display server. Antelope is an environmental data collection software package from Boulder Real Time Technologies (BRTT) typically used for very large seismic networks and real-time seismic data analyses. The primary processing engine produces continuous time-dependent response spectra for incoming acceleration streams. It utilizes expanded floating-point data representations within object ring-buffer packets and waveform files in a relational database. This leads to a very fast method for computing response spectra for a large number of channels. A Python script evaluates these response spectra for exceedance of one or more specified spectral limits, reporting any such exceedances via alarm packets that are put in the object ring-buffer for use by any alarm processes that need them. The web-display subsystem allows alert dissemination, interactive exploration, and alarm cancellation via the WWW.

Political skill: A proactive inhibitor of workplace aggression exposure and an active buffer of the aggression-strain relationship.

PubMed

Zhou, Zhiqing E; Yang, Liu-Qin; Spector, Paul E

2015-10-01

In the current study we examined the role of 4 dimensions of political skill (social astuteness, interpersonal influence, networking ability, and apparent sincerity) in predicting subsequent workplace aggression exposure based on the proactive coping framework. Further, we investigated their buffering effects on the negative outcomes of experienced workplace aggression based on the transactional stress model. Data were collected from nurses at 3 time points: before graduation (Time 1, n = 346), approximately 6 months after graduation (Time 2, n = 214), and approximately 12 months after graduation (Time 3, n = 161). Results showed that Time 1 interpersonal influence and apparent sincerity predicted subsequent physical aggression exposure. Exposure to physical and/or psychological workplace aggression was related to increased anger and musculoskeletal injury, and decreased job satisfaction and career commitment. Further, all dimensions of political skill but networking ability buffered some negative effects of physical aggression, and all dimensions but social astuteness buffered some negative effects of psychological aggression. (c) 2015 APA, all rights reserved).

Transformation rules and degradation of CAHs by Fentonlike oxidation in growth ring of water distribution network-A review

NASA Astrophysics Data System (ADS)

Zhong, D.; Ma, W. C.; Jiang, X. Q.; Yuan, Y. X.; Yuan, Y.; Wang, Z. Q.; Fang, T. T.; Huang, W. Y.

2017-08-01

Chlorinated hydrocarbons are widely used as organic solvent and chemical raw materials. After treatment, water polluted with trichloroethylene (TCE)/tetrachloroethylene (PCE) can reach the water quality requirements, while water with trace amounts of TCE/PCE is still harmful to humans, which will cause cancers. Water distribution network is an extremely complicated system, in which adsorption, desorption, flocculation, movement, transformation and reduction will occur, leading to changes of TCE/PCE concentrations and products. Therefore, it is important to investigate the transformation rules of TCE/PCE in water distribution network. What’s more, growth-ring, including drinking water pipes deposits, can act as catalysts in Fenton-like reagent (H2O2). This review summarizes the status of transformation rules of CAHs in water distribution network. It also evaluates the effectiveness and fruit of CAHs degradation by Fenton-like reagent based on growth-ring. This review is important in solving the potential safety problems caused by TCE/PCE in water distribution network.

Protocol for buffer space negotiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nessett, D.

There are at least two ways to manage the buffer memory of a communications node. On etechnique veiws the buffer as a single resource that is to be reserved and released as a unit for a particular communication transaction. A more common approach treats the node's buffer space as a collection of resources (e.g., bytes, words, packet slots) capable of being allocated among multiple concurrent conversations. To achieve buffer space multiplexing, some sort of negotiation for buffer space must take place between source and sink nodes before a transaction can commence. Results are presented which indicate that, for an applicationmore » involving a CSMA broadcast network, buffer space multiplexing offers better performance than buffer reservation. To achieve this improvement, a simple protocol is presented that features flow-control information traveling both from source to sink as well as from sink to source. It is argued that this bidirectionality allows the sink to allocate buffer space among its active communication paths more effectively. 13 figures.« less

Highly designable phenotypes and mutational buffers emerge from a systematic mapping between network topology and dynamic output.

PubMed

Nochomovitz, Yigal D; Li, Hao

2006-03-14

Deciphering the design principles for regulatory networks is fundamental to an understanding of biological systems. We have explored the mapping from the space of network topologies to the space of dynamical phenotypes for small networks. Using exhaustive enumeration of a simple model of three- and four-node networks, we demonstrate that certain dynamical phenotypes can be generated by an atypically broad spectrum of network topologies. Such dynamical outputs are highly designable, much like certain protein structures can be designed by an unusually broad spectrum of sequences. The network topologies that encode a highly designable dynamical phenotype possess two classes of connections: a fully conserved core of dedicated connections that encodes the stable dynamical phenotype and a partially conserved set of variable connections that controls the transient dynamical flow. By comparing the topologies and dynamics of the three- and four-node network ensembles, we observe a large number of instances of the phenomenon of "mutational buffering," whereby addition of a fourth node suppresses phenotypic variation amongst a set of three-node networks.

Design of an All-Optical Network Based on LCoS Technologies

NASA Astrophysics Data System (ADS)

Cheng, Yuh-Jiuh; Shiau, Yhi

2016-06-01

In this paper, an all-optical network composed of the ROADMs (reconfigurable optical add-drop multiplexer), L2/L3 optical packet switches, and the fiber optical cross-connection for fiber scheduling and measurement based on LCoS (liquid crystal on silicon) technologies is proposed. The L2/L3 optical packet switches are designed with optical output buffers. Only the header of optical packets is converted to electronic signals to control the wavelength of input ports and the packet payloads can be transparently destined to their output ports. An optical output buffer is designed to queue the packets when more than one incoming packet should reach to the same destination output port. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The wavelength of input ports is designed for routing incoming packets using LCoS technologies. Finally, the proposed OFS (optical flow switch) with input buffers can quickly transfer the big data to the output ports and the main purpose of the OFS is to reduce the number of wavelength reflections. The all-optical content delivery network is comprised of the OFSs for a large amount of audio and video data transmissions in the future.

Buffered coscheduling for parallel programming and enhanced fault tolerance

DOEpatents

Petrini, Fabrizio [Los Alamos, NM; Feng, Wu-chun [Los Alamos, NM

2006-01-31

A computer implemented method schedules processor jobs on a network of parallel machine processors or distributed system processors. Control information communications generated by each process performed by each processor during a defined time interval is accumulated in buffers, where adjacent time intervals are separated by strobe intervals for a global exchange of control information. A global exchange of the control information communications at the end of each defined time interval is performed during an intervening strobe interval so that each processor is informed by all of the other processors of the number of incoming jobs to be received by each processor in a subsequent time interval. The buffered coscheduling method of this invention also enhances the fault tolerance of a network of parallel machine processors or distributed system processors

High-port low-latency optical switch architecture with optical feed-forward buffering for 256-node disaggregated data centers.

PubMed

Terzenidis, Nikos; Moralis-Pegios, Miltiadis; Mourgias-Alexandris, George; Vyrsokinos, Konstantinos; Pleros, Nikos

2018-04-02

Departing from traditional server-centric data center architectures towards disaggregated systems that can offer increased resource utilization at reduced cost and energy envelopes, the use of high-port switching with highly stringent latency and bandwidth requirements becomes a necessity. We present an optical switch architecture exploiting a hybrid broadcast-and-select/wavelength routing scheme with small-scale optical feedforward buffering. The architecture is experimentally demonstrated at 10Gb/s, reporting error-free performance with a power penalty of <2.5dB. Moreover, network simulations for a 256-node system, revealed low-latency values of only 605nsec, at throughput values reaching 80% when employing 2-packet-size optical buffers, while multi-rack network performance was also investigated.

Connecting Seasonal Riparian Buffer Metrics and Nitrogen Concentrations in a Pulse-Driven Agricultural System

EPA Science Inventory

Riparian buffers have been well studied as best management practices for nutrient reduction at field scales yet their effectiveness for bettering water quality at watershed scales has been difficult to determine. Seasonal dynamics of the stream network are often overlooked when ...

Logistics of community smallpox control through contact tracing and ring vaccination: a stochastic network model.

PubMed

Porco, Travis C; Holbrook, Karen A; Fernyak, Susan E; Portnoy, Diane L; Reiter, Randy; Aragón, Tomás J

2004-08-06

Previous smallpox ring vaccination models based on contact tracing over a network suggest that ring vaccination would be effective, but have not explicitly included response logistics and limited numbers of vaccinators. We developed a continuous-time stochastic simulation of smallpox transmission, including network structure, post-exposure vaccination, vaccination of contacts of contacts, limited response capacity, heterogeneity in symptoms and infectiousness, vaccination prior to the discontinuation of routine vaccination, more rapid diagnosis due to public awareness, surveillance of asymptomatic contacts, and isolation of cases. We found that even in cases of very rapidly spreading smallpox, ring vaccination (when coupled with surveillance) is sufficient in most cases to eliminate smallpox quickly, assuming that 95% of household contacts are traced, 80% of workplace or social contacts are traced, and no casual contacts are traced, and that in most cases the ability to trace 1-5 individuals per day per index case is sufficient. If smallpox is assumed to be transmitted very quickly to contacts, it may at times escape containment by ring vaccination, but could be controlled in these circumstances by mass vaccination. Small introductions of smallpox are likely to be easily contained by ring vaccination, provided contact tracing is feasible. Uncertainties in the nature of bioterrorist smallpox (infectiousness, vaccine efficacy) support continued planning for ring vaccination as well as mass vaccination. If initiated, ring vaccination should be conducted without delays in vaccination, should include contacts of contacts (whenever there is sufficient capacity) and should be accompanied by increased public awareness and surveillance.

Dynamic states of a unidirectional ring of chen oscillators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carvalho, Ana; Pinto, Carla M.A.

2015-03-10

We study curious dynamical patterns appearing in a network of a unidirectional ring of Chen oscillators coupled to a ‘buffer’ cell. The network has Z{sub 3} exact symmetry group. We simulate the coupled cell systems associated to the two networks and obtain steady-states, rotating waves, quasiperiodic behavior, and chaos. The different patterns appear to arise through a sequence of Hopf, period-doubling and period-halving bifurcations. The network architecture appears to explain some patterns, whereas the properties of the chaotic oscillator may explain others. We use XPPAUT and MATLAB to compute numerically the relevant states.

Executing scatter operation to parallel computer nodes by repeatedly broadcasting content of send buffer partition corresponding to each node upon bitwise OR operation

DOEpatents

Archer, Charles J [Rochester, MN; Ratterman, Joseph D [Rochester, MN

2009-11-06

Executing a scatter operation on a parallel computer includes: configuring a send buffer on a logical root, the send buffer having positions, each position corresponding to a ranked node in an operational group of compute nodes and for storing contents scattered to that ranked node; and repeatedly for each position in the send buffer: broadcasting, by the logical root to each of the other compute nodes on a global combining network, the contents of the current position of the send buffer using a bitwise OR operation, determining, by each compute node, whether the current position in the send buffer corresponds with the rank of that compute node, if the current position corresponds with the rank, receiving the contents and storing the contents in a reception buffer of that compute node, and if the current position does not correspond with the rank, discarding the contents.

Modeling of price and profit in coupled-ring networks

NASA Astrophysics Data System (ADS)

Tangmongkollert, Kittiwat; Suwanna, Sujin

2016-06-01

We study the behaviors of magnetization, price, and profit profiles in ring networks in the presence of the external magnetic field. The Ising model is used to determine the state of each node, which is mapped to the buy-or-sell state in a financial market, where +1 is identified as the buying state, and -1 as the selling state. Price and profit mechanisms are modeled based on the assumption that price should increase if demand is larger than supply, and it should decrease otherwise. We find that the magnetization can be induced between two rings via coupling links, where the induced magnetization strength depends on the number of the coupling links. Consequently, the price behaves linearly with time, where its rate of change depends on the magnetization. The profit grows like a quadratic polynomial with coefficients dependent on the magnetization. If two rings have opposite direction of net spins, the price flows in the direction of the majority spins, and the network with the minority spins gets a loss in profit.

Group-multicast capable optical virtual private ring with contention avoidance

NASA Astrophysics Data System (ADS)

Peng, Yunfeng; Du, Shu; Long, Keping

2008-11-01

A ring based optical virtual private network (OVPN) employing contention sensing and avoidance is proposed to deliver multiple-to-multiple group-multicast traffic. The network architecture is presented and its operation principles as well as performance are investigated. The main contribution of this article is the presentation of an innovative group-multicast capable OVPN architecture with technologies available today.

Robust Adaptive Synchronization of Ring Configured Uncertain Chaotic FitzHugh–Nagumo Neurons under Direction-Dependent Coupling

PubMed Central

Iqbal, Muhammad; Rehan, Muhammad; Hong, Keum-Shik

2018-01-01

This paper exploits the dynamical modeling, behavior analysis, and synchronization of a network of four different FitzHugh–Nagumo (FHN) neurons with unknown parameters linked in a ring configuration under direction-dependent coupling. The main purpose is to investigate a robust adaptive control law for the synchronization of uncertain and perturbed neurons, communicating in a medium of bidirectional coupling. The neurons are assumed to be different and interconnected in a ring structure. The strength of the gap junctions is taken to be different for each link in the network, owing to the inter-neuronal coupling medium properties. Robust adaptive control mechanism based on Lyapunov stability analysis is employed and theoretical criteria are derived to realize the synchronization of the network of four FHN neurons in a ring form with unknown parameters under direction-dependent coupling and disturbances. The proposed scheme for synchronization of dissimilar neurons, under external electrical stimuli, coupled in a ring communication topology, having all parameters unknown, and subject to directional coupling medium and perturbations, is addressed for the first time as per our knowledge. To demonstrate the efficacy of the proposed strategy, simulation results are provided. PMID:29535622

High-Speed Ring Bus

NASA Technical Reports Server (NTRS)

Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

2010-01-01

The high-speed ring bus at the Jet Propulsion Laboratory (JPL) allows for future growth trends in spacecraft seen with future scientific missions. This innovation constitutes an enhancement of the 1393 bus as documented in the Institute of Electrical and Electronics Engineers (IEEE) 1393-1999 standard for a spaceborne fiber-optic data bus. It allows for high-bandwidth and time synchronization of all nodes on the ring. The JPL ring bus allows for interconnection of active units with autonomous operation and increased fault handling at high bandwidths. It minimizes the flight software interface with an intelligent physical layer design that has few states to manage as well as simplified testability. The design will soon be documented in the AS-1393 standard (Serial Hi-Rel Ring Network for Aerospace Applications). The framework is designed for "Class A" spacecraft operation and provides redundant data paths. It is based on "fault containment regions" and "redundant functional regions (RFR)" and has a method for allocating cables that completely supports the redundancy in spacecraft design, allowing for a complete RFR to fail. This design reduces the mass of the bus by incorporating both the Control Unit and the Data Unit in the same hardware. The standard uses ATM (asynchronous transfer mode) packets, standardized by ITU-T, ANSI, ETSI, and the ATM Forum. The IEEE-1393 standard uses the UNI form of the packet and provides no protection for the data portion of the cell. The JPL design adds optional formatting to this data portion. This design extends fault protection beyond that of the interconnect. This includes adding protection to the data portion that is contained within the Bus Interface Units (BIUs) and by adding to the signal interface between the Data Host and the JPL 1393 Ring Bus. Data transfer on the ring bus does not involve a master or initiator. Following bus protocol, any BIU may transmit data on the ring whenever it has data received from its host. There is no centralized arbitration or bus granting. The JPL design provides for autonomous synchronization of the nodes on the ring bus. An address-synchronous latency adjust buffer (LAB) has been designed that cannot get out of synchronization and needs no external input. Also, a priority-driven cable selection behavior has been programmed into each unit on the ring bus. This makes the bus able to connect itself up, according to a maximum redundancy priority system, without the need for computer intervention at startup. Switching around a failed or switched-off unit is also autonomous. The JPL bus provides a map of all the active units for the host computer to read and use for fault management. With regard to timing, this enhanced bus recognizes coordinated timing on a spacecraft as critical and addresses this with a single source of absolute and relative time, which is broadcast to all units on the bus with synchronization maintained to the tens of nanoseconds. Each BIU consists of up to five programmable triggers, which may be programmed for synchronization of events within the spacecraft of instrument. All JPL-formatted data transmitted on the ring bus are automatically time-stamped.

[Correction of the endothelial function damaged by gamma-irradiation with free and liposomal quercetin].

PubMed

Kyslova, O V; Sapatyĭ, A L; Kupnovyts'ka, I H; Moĭbenko, O O

2007-01-01

It has been investigation the action of solubil quercetin (corvitin) and quercetin filled liposomes (lipoflavon) on endothelium--dependent r-irradiated isolated rats aortic rings relaxations to acetylcholine. It has been showed, that corvitin addition directly to the buffer solution (0.1 mg/ml) increase endothelium--dependent vascular responses to acetylcholine on 35%, lipoflavon addition--on 25%.

Quality of Service for Real-Time Applications Over Next Generation Data Networks

NASA Technical Reports Server (NTRS)

Ivancic, William; Atiquzzaman, Mohammed; Bai, Haowei; Su, Hongjun; Jain, Raj; Duresi, Arjan; Goyal, Mukyl; Bharani, Venkata; Liu, Chunlei; Kota, Sastri

2001-01-01

This project, which started on January 1, 2000, was funded by NASA Glenn Research Center for duration of one year. The deliverables of the project included the following tasks: Study of QoS mapping between the edge and core networks envisioned in the Next Generation networks will provide us with the QoS guarantees that can be obtained from next generation networks. Buffer management techniques to provide strict guarantees to real-time end-to-end applications through preferential treatment to packets belonging to real-time applications. In particular, use of ECN to help reduce the loss on high bandwidth-delay product satellite networks needs to be studied. Effect of Prioritized Packet Discard to increase goodput of the network and reduce the buffering requirements in the ATM switches. Provision of new IP circuit emulation services over Satellite IP backbones using MPLS will be studied. Determine the architecture and requirements for internetworking ATN and the Next Generation Internet for real-time applications.

Mechanisms Underlying the Active Self-Assembly of Microtubule Rings and Spools.

PubMed

VanDelinder, Virginia; Brener, Stephanie; Bachand, George D

2016-03-14

Active self-assembly offers a powerful route for the creation of dynamic multiscale structures that are presently inaccessible with standard microfabrication techniques. One such system uses the translation of microtubule filaments by surface-tethered kinesin to actively assemble nanocomposites with bundle, ring, and spool morphologies. Attempts to observe mechanisms involved in this active assembly system have been hampered by experimental difficulties with performing observation during buffer exchange and photodamage from fluorescent excitation. In the present work, we used a custom microfluidic device to remove these limitations and directly study ring/spool formation, including the earliest events (nucleation) that drive subsequent nanocomposite assembly. Three distinct formation events were observed: pinning, collisions, and induced curvature. Of these three, collisions accounted for the majority of event leading to ring/spool formation, while the rate of pinning was shown to be dependent on the amount of photodamage in the system. We further showed that formation mechanism directly affects the diameter and rotation direction of the resultant rings and spools. Overall, the fundamental understanding described in this work provides a foundation by which the properties of motor-driven, actively assembled nanocomposites may be tailored toward specific applications.

Mechanisms underlying the active self-assembly of microtubule rings and spools

DOE PAGES

VanDelinder, Virginia; Brener, Stephanie; Bachand, George D.

2016-02-04

Here, active self-assembly offers a powerful route for the creation of dynamic multiscale structures that are presently inaccessible with standard microfabrication techniques. One such system uses the translation of microtubule filaments by surface-tethered kinesin to actively assemble nanocomposites with bundle, ring, and spool morphologies. Attempts to observe mechanisms involved in this active assembly system have been hampered by experimental difficulties with performing observation during buffer exchange and photodamage from fluorescent excitation. In the present work, we used a custom microfluidic device to remove these limitations and directly study ring/spool formation, including the earliest events (nucleation) that drive subsequent nanocomposite assembly.more » Three distinct formation events were observed: pinning, collisions, and induced curvature. Of these three, collisions accounted for the majority of event leading to ring/spool formation, while the rate of pinning was shown to be dependent on the amount of photodamage in the system. We further showed that formation mechanism directly affects the diameter and rotation direction of the resultant rings and spools. Overall, the fundamental understanding described in this work provides a foundation by which the properties of motor-driven, actively assembled nanocomposites may be tailored toward specific applications.« less

Using simple agent-based modeling to inform and enhance neighborhood walkability.

PubMed

Badland, Hannah; White, Marcus; Macaulay, Gus; Eagleson, Serryn; Mavoa, Suzanne; Pettit, Christopher; Giles-Corti, Billie

2013-12-11

Pedestrian-friendly neighborhoods with proximal destinations and services encourage walking and decrease car dependence, thereby contributing to more active and healthier communities. Proximity to key destinations and services is an important aspect of the urban design decision making process, particularly in areas adopting a transit-oriented development (TOD) approach to urban planning, whereby densification occurs within walking distance of transit nodes. Modeling destination access within neighborhoods has been limited to circular catchment buffers or more sophisticated network-buffers generated using geoprocessing routines within geographical information systems (GIS). Both circular and network-buffer catchment methods are problematic. Circular catchment models do not account for street networks, thus do not allow exploratory 'what-if' scenario modeling; and network-buffering functionality typically exists within proprietary GIS software, which can be costly and requires a high level of expertise to operate. This study sought to overcome these limitations by developing an open-source simple agent-based walkable catchment tool that can be used by researchers, urban designers, planners, and policy makers to test scenarios for improving neighborhood walkable catchments. A simplified version of an agent-based model was ported to a vector-based open source GIS web tool using data derived from the Australian Urban Research Infrastructure Network (AURIN). The tool was developed and tested with end-user stakeholder working group input. The resulting model has proven to be effective and flexible, allowing stakeholders to assess and optimize the walkability of neighborhood catchments around actual or potential nodes of interest (e.g., schools, public transport stops). Users can derive a range of metrics to compare different scenarios modeled. These include: catchment area versus circular buffer ratios; mean number of streets crossed; and modeling of different walking speeds and wait time at intersections. The tool has the capacity to influence planning and public health advocacy and practice, and by using open-access source software, it is available for use locally and internationally. There is also scope to extend this version of the tool from a simple to a complex model, which includes agents (i.e., simulated pedestrians) 'learning' and incorporating other environmental attributes that enhance walkability (e.g., residential density, mixed land use, traffic volume).

ACCURATE CHEMICAL MASTER EQUATION SOLUTION USING MULTI-FINITE BUFFERS

PubMed Central

Cao, Youfang; Terebus, Anna; Liang, Jie

2016-01-01

The discrete chemical master equation (dCME) provides a fundamental framework for studying stochasticity in mesoscopic networks. Because of the multi-scale nature of many networks where reaction rates have large disparity, directly solving dCMEs is intractable due to the exploding size of the state space. It is important to truncate the state space effectively with quantified errors, so accurate solutions can be computed. It is also important to know if all major probabilistic peaks have been computed. Here we introduce the Accurate CME (ACME) algorithm for obtaining direct solutions to dCMEs. With multi-finite buffers for reducing the state space by O(n!), exact steady-state and time-evolving network probability landscapes can be computed. We further describe a theoretical framework of aggregating microstates into a smaller number of macrostates by decomposing a network into independent aggregated birth and death processes, and give an a priori method for rapidly determining steady-state truncation errors. The maximal sizes of the finite buffers for a given error tolerance can also be pre-computed without costly trial solutions of dCMEs. We show exactly computed probability landscapes of three multi-scale networks, namely, a 6-node toggle switch, 11-node phage-lambda epigenetic circuit, and 16-node MAPK cascade network, the latter two with no known solutions. We also show how probabilities of rare events can be computed from first-passage times, another class of unsolved problems challenging for simulation-based techniques due to large separations in time scales. Overall, the ACME method enables accurate and efficient solutions of the dCME for a large class of networks. PMID:27761104

Final Report for File System Support for Burst Buffers on HPC Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, W.; Mohror, K.

Distributed burst buffers are a promising storage architecture for handling I/O workloads for exascale computing. As they are being deployed on more supercomputers, a file system that efficiently manages these burst buffers for fast I/O operations carries great consequence. Over the past year, FSU team has undertaken several efforts to design, prototype and evaluate distributed file systems for burst buffers on HPC systems. These include MetaKV: a Key-Value Store for Metadata Management of Distributed Burst Buffers, a user-level file system with multiple backends, and a specialized file system for large datasets of deep neural networks. Our progress for these respectivemore » efforts are elaborated further in this report.« less

Simulated Tree Growth across the Northern Hemisphere and the Seasonality of Climate Signals Encoded within Tree-ring Widths

NASA Astrophysics Data System (ADS)

Li, X.; St George, S.

2013-12-01

Both dendrochronological theory and regional and global networks of tree-ring width measurements indicate that trees can respond to climate variations quite differently from one location to another. To explain these geographical differences at hemispheric scale, we used a process-based model of tree-ring formation (the Vaganov-Shashkin model) to simulate tree growth at over 6000 locations across the Northern Hemisphere. We compared the seasonality and strength of climate signals in the simulated tree-ring records against parallel analysis conducted on a hemispheric network of real tree-ring observations, tested the ability of the model to reproduce behaviors that emerge from large networks of tree-ring widths and used the model outputs to explain why the network exhibits these behaviors. The simulated tree-ring records are consistent with observations with respect to the seasonality and relative strength of the encoded climate signals, and time-related changes in these climate signals can be predicted using the modeled relative growth rate due to temperature or soil moisture. The positive imprint of winter (DJF) precipitation is strongest in simulations from the American Southwest and northern Mexico as well as selected locations in the Mediterranean and central Asia. Summer (JJA) precipitation has higher positive correlations with simulations in the mid-latitudes, but some high-latitude coastal sites exhibit a negative association. The influence of summer temperature is mainly positive at high-latitude or high-altitude sites and negative in the mid-latitudes. The absolute magnitude of climate correlations are generally higher in simulations than in observations, but the pattern and geographical differences remain the same, demonstrating that the model has skill in reproducing tree-ring growth response to climate variability in the Northern Hemisphere. Because the model uses only temperature, precipitation and latitude as input and is not adjusted for species or other biological factors, the fact that the climate response of the simulations largely agrees with the observations may imply that climate, rather than biology, is the main factor that influences large-scale patterns of the climate information recorded by tree rings. Our results also suggest that the Vaganov-Shashkin model could be used to estimate the likely climate response of trees in ';frontier' areas that have not been sampled extensively. Seasonal Climate Correlations of Simulated Tree-ring Records

USSR Report: Machine Tools and Metalworking Equipment.

DTIC Science & Technology

1986-01-23

between satellite stop and the camshaft of the programer unit. The line has 23 positions including 12 automatic ones. Specification of line Number...technological, processes, automated research, etc.) are as follows.: a monochannel based on a shared trunk line, ring, star and tree (polychannel...line or ring networks based on decentralized control of data exchange between subscribers are very robust. A tree -form network has star structure

A 250-Mbit/s ring local computer network using 1.3-microns single-mode optical fibers

NASA Technical Reports Server (NTRS)

Eng, S. T.; Tell, R.; Andersson, T.; Eng, B.

1985-01-01

A 250-Mbit/s three-station fiber-optic ring local computer network was built and successfully demonstrated. A conventional token protocol was employed for bus arbitration to maximize the bus efficiency under high loading conditions, and a non-return-to-zero (NRS) data encoding format was selected for simplicity and maximum utilization of the ECL-circuit bandwidth.

Ring-like reliable PON planning with physical constraints for a smart grid

NASA Astrophysics Data System (ADS)

Wang, Xin; Gu, Rentao; Ji, Yuefeng

2016-01-01

Due to the high reliability requirements in the communication networks of a smart grid, a ring-like reliable PON is an ideal choice to carry power distribution information. Economical network planning is also very important for the smart grid communication infrastructure. Although the ring-like reliable PON has been widely used in the real applications, as far as we know, little research has been done on the network optimization subject of the ring-like reliable PON. Most PON planning research studies only consider a star-like topology or cascaded PON network, which barely guarantees the reliability requirements of the smart grid. In this paper, we mainly investigate the economical network planning problem for the ring-like reliable PON of the smart grid. To address this issue, we built a mathematical model for the planning problem of the ring-like reliable PON, and the objective was to minimize the total deployment costs under physical constraints. The model is simplified such that all of the nodes have the same properties, except OLT, because each potential splitter site can be located in the same ONU position in power communication networks. The simplified model is used to construct an optimal main tree topology in the complete graph and a backup-protected tree topology in the residual graph. An efficient heuristic algorithm, called the Constraints and Minimal Weight Oriented Fast Searching Algorithm (CMW-FSA), is proposed. In CMW-FSA, a feasible solution can be obtained directly with oriented constraints and a few recursive search processes. From the simulation results, the proposed planning model and CMW-FSA are verified to be accurate (the error rates are less than 0.4%) and effective compared with the accurate solution (CAESA), especially in small and sparse scenarios. The CMW-FSA significantly reduces the computation time compared with the CAESA. The time complexity algorithm of the CMW-FSA is acceptable and calculated as T(n) = O(n3). After evaluating the effects of the parameters of the two PON systems, the total planning costs of each scenario show a general declining trend and reach a threshold as the respective maximal transmission distances and maximal time delays increase.

Delivering Faster Congestion Feedback with the Mark-Front Strategy

NASA Technical Reports Server (NTRS)

Liu, Chunlei; Jain, Raj

2001-01-01

Computer networks use congestion feedback from the routers and destinations to control the transmission load. Delivering timely congestion feedback is essential to the performance of networks. Reaction to the congestion can be more effective if faster feedback is provided. Current TCP/IP networks use timeout, duplicate Acknowledgement Packets (ACKs) and explicit congestion notification (ECN) to deliver the congestion feedback, each provides a faster feedback than the previous method. In this paper, we propose a markfront strategy that delivers an even faster congestion feedback. With analytical and simulation results, we show that mark-front strategy reduces buffer size requirement, improves link efficiency and provides better fairness among users. Keywords: Explicit Congestion Notification, mark-front, congestion control, buffer size requirement, fairness.

Noise-sustained synchronization between electrically coupled FitzHugh-Nagumo networks

NASA Astrophysics Data System (ADS)

Cascallares, Guadalupe; Sánchez, Alejandro D.; dell'Erba, Matías G.; Izús, Gonzalo G.

2015-09-01

We investigate the capability of electrical synapses to transmit the noise-sustained network activity from one network to another. The particular setup we consider is two identical rings with excitable FitzHugh-Nagumo cell dynamics and nearest-neighbor antiphase intra-ring coupling, electrically coupled between corresponding nodes. The whole system is submitted to independent local additive Gaussian white noises with common intensity η, but only one ring is externally forced by a global adiabatic subthreshold harmonic signal. We then seek conditions for a particular noise level to promote synchronized stable firing patterns. By running numerical integrations with increasing η, we observe the excitation activity to become spatiotemporally self-organized, until η is so strong that spoils sync between networks for a given value of the electric coupling strength. By means of a four-cell model and calculating the stationary probability distribution, we obtain a (signal-dependent) non-equilibrium potential landscape which explains qualitatively the observed regimes, and whose barrier heights give a good estimate of the optimal noise intensity for the sync between networks.

Self-healing ring-based WDM-PON

NASA Astrophysics Data System (ADS)

Zhou, Yang; Gan, Chaoqin; Zhu, Long

2010-05-01

In this paper, a survivable ring-based wavelength-division-multiplexing (WDM)-passive optical network (PON) for fiber protection is proposed. Protections for feeder fiber and distributed fiber are independent in the scheme. Optical line terminal (OLT) and optical network units (ONUs) can automatically switch to protection link when fiber failure occurs. Protection distributed fiber is not required in the scheme. Cost-effective components are used in ONUs to minimize costs of network. A simulation study is performed to demonstrate the scheme. Its result shows good performance of upstream and downstream signals.

Simple Algorithms for Distributed Leader Election in Anonymous Synchronous Rings and Complete Networks Inspired by Neural Development in Fruit Flies.

PubMed

Xu, Lei; Jeavons, Peter

2015-11-01

Leader election in anonymous rings and complete networks is a very practical problem in distributed computing. Previous algorithms for this problem are generally designed for a classical message passing model where complex messages are exchanged. However, the need to send and receive complex messages makes such algorithms less practical for some real applications. We present some simple synchronous algorithms for distributed leader election in anonymous rings and complete networks that are inspired by the development of the neural system of the fruit fly. Our leader election algorithms all assume that only one-bit messages are broadcast by nodes in the network and processors are only able to distinguish between silence and the arrival of one or more messages. These restrictions allow implementations to use a simpler message-passing architecture. Even with these harsh restrictions our algorithms are shown to achieve good time and message complexity both analytically and experimentally.

A simple, effective media access protocol system for integrated, high data rate networks

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, K.; Overstreet, C. M.; Khanna, S.; Zhang, L.

1992-01-01

The operation and performance of a dual media access protocol for integrated, gigabit networks are described. Unlike other dual protocols, each protocol supports a different class of traffic. The Carrier Sensed Multiple Access-Ring Network (CSMA/RN) protocol and the Circulating Reservation Packet (CRP) protocol support asynchronous and synchronous traffic, respectively. The two protocols operate with minimal impact upon each other. Performance information demonstrates that they support a complete range of integrated traffic loads, do not require call setup/termination or a special node for synchronous traffic control, and provide effective pre-use and recovery. The CRP also provides guaranteed access and fairness control for the asynchronous system. The paper demonstrates that the CSMA-CRP system fulfills many of the requirements for gigabit LAN-MAN networks most effectively and simply. To accomplish this, CSMA-CRP features are compared against similar ring and bus systems, such as Cambridge Fast Ring, Metaring, Cyclic Reservation Multiple Access, and Distributed Dual Queue Data Bus (DQDB).

Adaptive Resource Utilization Prediction System for Infrastructure as a Service Cloud.

PubMed

Zia Ullah, Qazi; Hassan, Shahzad; Khan, Gul Muhammad

2017-01-01

Infrastructure as a Service (IaaS) cloud provides resources as a service from a pool of compute, network, and storage resources. Cloud providers can manage their resource usage by knowing future usage demand from the current and past usage patterns of resources. Resource usage prediction is of great importance for dynamic scaling of cloud resources to achieve efficiency in terms of cost and energy consumption while keeping quality of service. The purpose of this paper is to present a real-time resource usage prediction system. The system takes real-time utilization of resources and feeds utilization values into several buffers based on the type of resources and time span size. Buffers are read by R language based statistical system. These buffers' data are checked to determine whether their data follows Gaussian distribution or not. In case of following Gaussian distribution, Autoregressive Integrated Moving Average (ARIMA) is applied; otherwise Autoregressive Neural Network (AR-NN) is applied. In ARIMA process, a model is selected based on minimum Akaike Information Criterion (AIC) values. Similarly, in AR-NN process, a network with the lowest Network Information Criterion (NIC) value is selected. We have evaluated our system with real traces of CPU utilization of an IaaS cloud of one hundred and twenty servers.

Adaptive Resource Utilization Prediction System for Infrastructure as a Service Cloud

PubMed Central

Hassan, Shahzad; Khan, Gul Muhammad

2017-01-01

Infrastructure as a Service (IaaS) cloud provides resources as a service from a pool of compute, network, and storage resources. Cloud providers can manage their resource usage by knowing future usage demand from the current and past usage patterns of resources. Resource usage prediction is of great importance for dynamic scaling of cloud resources to achieve efficiency in terms of cost and energy consumption while keeping quality of service. The purpose of this paper is to present a real-time resource usage prediction system. The system takes real-time utilization of resources and feeds utilization values into several buffers based on the type of resources and time span size. Buffers are read by R language based statistical system. These buffers' data are checked to determine whether their data follows Gaussian distribution or not. In case of following Gaussian distribution, Autoregressive Integrated Moving Average (ARIMA) is applied; otherwise Autoregressive Neural Network (AR-NN) is applied. In ARIMA process, a model is selected based on minimum Akaike Information Criterion (AIC) values. Similarly, in AR-NN process, a network with the lowest Network Information Criterion (NIC) value is selected. We have evaluated our system with real traces of CPU utilization of an IaaS cloud of one hundred and twenty servers. PMID:28811819

Expanding the network of crossdated tree-ring chronologies for Sequoia sempervirens

Treesearch

Allyson L. Carroll; Stephen C. Sillett; Ethan J. Coonen; Benjamin G. Iberle

2017-01-01

Crossdated tree-ring chronologies for the Arcata Community Forest (ACF) and Muir Woods National Monument (Muir Woods) expand the spatial coverage of dated coast redwood (Sequoia sempervirens (D. Don) Endl.) series. Crossdating relies on the common pattern of ring-width variation among tree populations, and dated chronologies have many applications...

Modeling synchronization in networks of delay-coupled fiber ring lasers.

PubMed

Lindley, Brandon S; Schwartz, Ira B

2011-11-21

We study the onset of synchronization in a network of N delay-coupled stochastic fiber ring lasers with respect to various parameters when the coupling power is weak. In particular, for groups of three or more ring lasers mutually coupled to a central hub laser, we demonstrate a robust tendency toward out-of-phase (achronal) synchronization between the N-1 outer lasers and the single inner laser. In contrast to the achronal synchronization, we find the outer lasers synchronize with zero-lag (isochronal) with respect to each other, thus forming a set of N-1 coherent fiber lasers. © 2011 Optical Society of America

Interactions with parents and friends among chronically ill children: examining social networks.

PubMed

Herzer, Michele; Umfress, Kris; Aljadeff, Gabriel; Ghai, Kanika; Zakowski, Sandra G

2009-12-01

Children with medical conditions often experience a combination of positive and negative social interactions with parents and friends. Adult research examining cross-domain buffering effects has documented that supportive social ties can make up for shortcomings in other social relationships. This study examined whether negative effects of strained relationships with loved ones can be buffered when children feel supported by individuals in different support networks (i.e., cross-domain buffering effects). Children with Type I diabetes (n = 56), chronic asthma (n = 54), and cystic fibrosis (n = 17) completed questionnaires during an outpatient hospital visit that assessed perceptions of support and strain from parents and friends, quality of life, self-concept, and emotional/behavioral difficulties. Parental strain was conceptualized as parental overprotection and parental rejection. Hierarchical regression analyses showed that friend support buffered the adverse effects of parental strain on child quality of life, self-concept, and emotional/behavioral difficulties. Interestingly, parental support did not buffer the negative effects of experiencing strained relationships with friends; only main effects on outcome were found. These findings partially support our hypotheses of cross-domain buffering. In this study, friendships were a protective factor for children who experienced strained relationships with parents. In contrast, although parent support had a direct impact on child outcome, it did not make up for feeling rejected by friends. Because close relationships are often strained during medical stressors, findings underscore the importance of promoting social connectedness in chronically ill children to maximize opportunities for experiencing positive social relationships.

The effect of social networks and social support on common mental disorders following specific life events.

PubMed

Maulik, P K; Eaton, W W; Bradshaw, C P

2010-08-01

This study examined the association between life events and common mental disorders while accounting for social networks and social supports. Participants included 1920 adults in the Baltimore Epidemiologic Catchment Area Cohort who were interviewed in 1993-1996, of whom 1071 were re-interviewed in 2004-2005. Generalized estimating equations were used to analyze the data. Social support from friends, spouse or relatives was associated with significantly reduced odds of panic disorder and psychological distress, after experiencing specific life events. Social networks or social support had no significant stress-buffering effect. Social networks and social support had almost no direct or buffering effect on major depressive disorder, and no effect on generalized anxiety disorder and alcohol abuse or dependence disorder. The significant association between social support and psychological distress, rather than diagnosable mental disorders, highlights the importance of social support, especially when the severity of a mental health related problem is low.

Vascular tissue engineering by computer-aided laser micromachining.

PubMed

Doraiswamy, Anand; Narayan, Roger J

2010-04-28

Many conventional technologies for fabricating tissue engineering scaffolds are not suitable for fabricating scaffolds with patient-specific attributes. For example, many conventional technologies for fabricating tissue engineering scaffolds do not provide control over overall scaffold geometry or over cell position within the scaffold. In this study, the use of computer-aided laser micromachining to create scaffolds for vascular tissue networks was investigated. Computer-aided laser micromachining was used to construct patterned surfaces in agarose or in silicon, which were used for differential adherence and growth of cells into vascular tissue networks. Concentric three-ring structures were fabricated on agarose hydrogel substrates, in which the inner ring contained human aortic endothelial cells, the middle ring contained HA587 human elastin and the outer ring contained human aortic vascular smooth muscle cells. Basement membrane matrix containing vascular endothelial growth factor and heparin was to promote proliferation of human aortic endothelial cells within the vascular tissue networks. Computer-aided laser micromachining provides a unique approach to fabricate small-diameter blood vessels for bypass surgery as well as other artificial tissues with complex geometries.

Minimally buffered data transfers between nodes in a data communications network

DOEpatents

Miller, Douglas R.

2015-06-23

Methods, apparatus, and products for minimally buffered data transfers between nodes in a data communications network are disclosed that include: receiving, by a messaging module on an origin node, a storage identifier, a origin data type, and a target data type, the storage identifier specifying application storage containing data, the origin data type describing a data subset contained in the origin application storage, the target data type describing an arrangement of the data subset in application storage on a target node; creating, by the messaging module, origin metadata describing the origin data type; selecting, by the messaging module from the origin application storage in dependence upon the origin metadata and the storage identifier, the data subset; and transmitting, by the messaging module to the target node, the selected data subset for storing in the target application storage in dependence upon the target data type without temporarily buffering the data subset.

Physical activity and neighborhood resources in high school girls.

PubMed

Pate, Russell R; Colabianchi, Natalie; Porter, Dwayne; Almeida, Maria J; Lobelo, Felipe; Dowda, Marsha

2008-05-01

Physical activity behavior is influenced by a person's physical environment, but few studies have used objective measures to study the influences of the physical environment on physical activity behavior in youth. The purpose of this study was to examine the relationship between selected neighborhood physical activity resources and physical activity levels in high school girls. Participants were students in schools that had participated in a large physical activity intervention trial. The 3-Day Physical Activity Recall was completed by 1506 12th-grade girls. Data on physical activity facilities and resources in the participating communities were collected using a variety of methods. Physical activity resources within a 0.75-mile street-network buffer around each girl's home were counted using ArcGIS, version 9.1. Mixed-model regression models were used to determine if there was a relationship between three physical activity variables and the number of physical activity resources within the 0.75-mile buffer. Data were collected in 2002-2003 and analyzed in 2006-2007. On average, 3.5 physical activity resources (e.g., schools, parks, commercial facilities) were located within the 0.75-mile street-network buffer. Thirty-six percent of the girls had no physical activity resource within the buffer. When multiple physical activity resources were considered, the number of commercial physical activity facilities was significantly associated with reported vigorous physical activity, and the number of parks was associated with total METs in white girls. Multiple physical activity resources within a 0.75-mile street-network buffer around adolescent girls' homes are associated physical activity in those girls. Several types of resources are associated with vigorous physical activity and total activity in adolescent girls. Future studies should examine the temporal and causal relationships between the physical environment, physical activity, and health outcomes related to physical activity.

Mobility and Cloud: Operating in Intermittent, Austere Network Conditions

DTIC Science & Technology

2014-09-01

consume information, and are connected to cloud-based servers over wired or wireless network connections. For mobile clients, this connection, by...near future. In addition to intermittent connectivity issues, many wireless networks introduce additional delay due to excessive buffering. This can...requirements, commercial cloud applications have grown at a fast rate. Similar to other mobile systems, navy ships connected over wireless networks

Managing Network Partitions in Structured P2P Networks

NASA Astrophysics Data System (ADS)

Shafaat, Tallat M.; Ghodsi, Ali; Haridi, Seif

Structured overlay networks form a major class of peer-to-peer systems, which are touted for their abilities to scale, tolerate failures, and self-manage. Any long-lived Internet-scale distributed system is destined to face network partitions. Consequently, the problem of network partitions and mergers is highly related to fault-tolerance and self-management in large-scale systems. This makes it a crucial requirement for building any structured peer-to-peer systems to be resilient to network partitions. Although the problem of network partitions and mergers is highly related to fault-tolerance and self-management in large-scale systems, it has hardly been studied in the context of structured peer-to-peer systems. Structured overlays have mainly been studied under churn (frequent joins/failures), which as a side effect solves the problem of network partitions, as it is similar to massive node failures. Yet, the crucial aspect of network mergers has been ignored. In fact, it has been claimed that ring-based structured overlay networks, which constitute the majority of the structured overlays, are intrinsically ill-suited for merging rings. In this chapter, we motivate the problem of network partitions and mergers in structured overlays. We discuss how a structured overlay can automatically detect a network partition and merger. We present an algorithm for merging multiple similar ring-based overlays when the underlying network merges. We examine the solution in dynamic conditions, showing how our solution is resilient to churn during the merger, something widely believed to be difficult or impossible. We evaluate the algorithm for various scenarios and show that even when falsely detecting a merger, the algorithm quickly terminates and does not clutter the network with many messages. The algorithm is flexible as the tradeoff between message complexity and time complexity can be adjusted by a parameter.

Accurate chemical master equation solution using multi-finite buffers

DOE PAGES

Cao, Youfang; Terebus, Anna; Liang, Jie

2016-06-29

Here, the discrete chemical master equation (dCME) provides a fundamental framework for studying stochasticity in mesoscopic networks. Because of the multiscale nature of many networks where reaction rates have a large disparity, directly solving dCMEs is intractable due to the exploding size of the state space. It is important to truncate the state space effectively with quantified errors, so accurate solutions can be computed. It is also important to know if all major probabilistic peaks have been computed. Here we introduce the accurate CME (ACME) algorithm for obtaining direct solutions to dCMEs. With multifinite buffers for reducing the state spacemore » by $O(n!)$, exact steady-state and time-evolving network probability landscapes can be computed. We further describe a theoretical framework of aggregating microstates into a smaller number of macrostates by decomposing a network into independent aggregated birth and death processes and give an a priori method for rapidly determining steady-state truncation errors. The maximal sizes of the finite buffers for a given error tolerance can also be precomputed without costly trial solutions of dCMEs. We show exactly computed probability landscapes of three multiscale networks, namely, a 6-node toggle switch, 11-node phage-lambda epigenetic circuit, and 16-node MAPK cascade network, the latter two with no known solutions. We also show how probabilities of rare events can be computed from first-passage times, another class of unsolved problems challenging for simulation-based techniques due to large separations in time scales. Overall, the ACME method enables accurate and efficient solutions of the dCME for a large class of networks.« less

Accurate chemical master equation solution using multi-finite buffers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Youfang; Terebus, Anna; Liang, Jie

Here, the discrete chemical master equation (dCME) provides a fundamental framework for studying stochasticity in mesoscopic networks. Because of the multiscale nature of many networks where reaction rates have a large disparity, directly solving dCMEs is intractable due to the exploding size of the state space. It is important to truncate the state space effectively with quantified errors, so accurate solutions can be computed. It is also important to know if all major probabilistic peaks have been computed. Here we introduce the accurate CME (ACME) algorithm for obtaining direct solutions to dCMEs. With multifinite buffers for reducing the state spacemore » by $O(n!)$, exact steady-state and time-evolving network probability landscapes can be computed. We further describe a theoretical framework of aggregating microstates into a smaller number of macrostates by decomposing a network into independent aggregated birth and death processes and give an a priori method for rapidly determining steady-state truncation errors. The maximal sizes of the finite buffers for a given error tolerance can also be precomputed without costly trial solutions of dCMEs. We show exactly computed probability landscapes of three multiscale networks, namely, a 6-node toggle switch, 11-node phage-lambda epigenetic circuit, and 16-node MAPK cascade network, the latter two with no known solutions. We also show how probabilities of rare events can be computed from first-passage times, another class of unsolved problems challenging for simulation-based techniques due to large separations in time scales. Overall, the ACME method enables accurate and efficient solutions of the dCME for a large class of networks.« less

Network protocols for real-time applications

NASA Technical Reports Server (NTRS)

Johnson, Marjory J.

1987-01-01

The Fiber Distributed Data Interface (FDDI) and the SAE AE-9B High Speed Ring Bus (HSRB) are emerging standards for high-performance token ring local area networks. FDDI was designed to be a general-purpose high-performance network. HSRB was designed specifically for military real-time applications. A workshop was conducted at NASA Ames Research Center in January, 1987 to compare and contrast these protocols with respect to their ability to support real-time applications. This report summarizes workshop presentations and includes an independent comparison of the two protocols. A conclusion reached at the workshop was that current protocols for the upper layers of the Open Systems Interconnection (OSI) network model are inadequate for real-time applications.

Optical resonators and neural networks

NASA Astrophysics Data System (ADS)

Anderson, Dana Z.

1986-08-01

It may be possible to implement neural network models using continuous field optical architectures. These devices offer the inherent parallelism of propagating waves and an information density in principle dictated by the wavelength of light and the quality of the bulk optical elements. Few components are needed to construct a relatively large equivalent network. Various associative memories based on optical resonators have been demonstrated in the literature, a ring resonator design is discussed in detail here. Information is stored in a holographic medium and recalled through a competitive processes in the gain medium supplying energy to the ring rsonator. The resonator memory is the first realized example of a neural network function implemented with this kind of architecture.

Influence of neural adaptation on dynamics and equilibrium state of neural activities in a ring neural network

NASA Astrophysics Data System (ADS)

Takiyama, Ken

2017-12-01

How neural adaptation affects neural information processing (i.e. the dynamics and equilibrium state of neural activities) is a central question in computational neuroscience. In my previous works, I analytically clarified the dynamics and equilibrium state of neural activities in a ring-type neural network model that is widely used to model the visual cortex, motor cortex, and several other brain regions. The neural dynamics and the equilibrium state in the neural network model corresponded to a Bayesian computation and statistically optimal multiple information integration, respectively, under a biologically inspired condition. These results were revealed in an analytically tractable manner; however, adaptation effects were not considered. Here, I analytically reveal how the dynamics and equilibrium state of neural activities in a ring neural network are influenced by spike-frequency adaptation (SFA). SFA is an adaptation that causes gradual inhibition of neural activity when a sustained stimulus is applied, and the strength of this inhibition depends on neural activities. I reveal that SFA plays three roles: (1) SFA amplifies the influence of external input in neural dynamics; (2) SFA allows the history of the external input to affect neural dynamics; and (3) the equilibrium state corresponds to the statistically optimal multiple information integration independent of the existence of SFA. In addition, the equilibrium state in a ring neural network model corresponds to the statistically optimal integration of multiple information sources under biologically inspired conditions, independent of the existence of SFA.

Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

PubMed

Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

2013-01-28

We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

Molecular transport network security using multi-wavelength optical spins.

PubMed

Tunsiri, Surachai; Thammawongsa, Nopparat; Mitatha, Somsak; Yupapin, Preecha P

2016-01-01

Multi-wavelength generation system using an optical spin within the modified add-drop optical filter known as a PANDA ring resonator for molecular transport network security is proposed. By using the dark-bright soliton pair control, the optical capsules can be constructed and applied to securely transport the trapped molecules within the network. The advantage is that the dark and bright soliton pair (components) can securely propagate for long distance without electromagnetic interference. In operation, the optical intensity from PANDA ring resonator is fed into gold nano-antenna, where the surface plasmon oscillation between soliton pair and metallic waveguide is established.

Demonstration and field trial of a resilient hybrid NG-PON test-bed

NASA Astrophysics Data System (ADS)

Prat, Josep; Polo, Victor; Schrenk, Bernhard; Lazaro, Jose A.; Bonada, Francesc; Lopez, Eduardo T.; Omella, Mireia; Saliou, Fabienne; Le, Quang T.; Chanclou, Philippe; Leino, Dmitri; Soila, Risto; Spirou, Spiros; Costa, Liliana; Teixeira, Antonio; Tosi-Beleffi, Giorgio M.; Klonidis, Dimitrios; Tomkos, Ioannis

2014-10-01

A multi-layer next generation PON prototype has been built and tested, to show the feasibility of extended hybrid DWDM/TDM-XGPON FTTH networks with resilient optically-integrated ring-trees architecture, supporting broadband multimedia services. It constitutes a transparent common platform for the coexistence of multiple operators sharing the optical infrastructure of the central metro ring, passively combining the access and the metropolitan network sections. It features 32 wavelength connections at 10 Gbps, up to 1000 users distributed in 16 independent resilient sub-PONs over 100 km. This paper summarizes the network operation, demonstration and field trial results.

New type of chimera structures in a ring of bistable FitzHugh-Nagumo oscillators with nonlocal interaction

NASA Astrophysics Data System (ADS)

Shepelev, I. A.; Vadivasova, T. E.; Bukh, A. V.; Strelkova, G. I.; Anishchenko, V. S.

2017-04-01

We study the spatiotemporal dynamics of a ring of nonlocally coupled FitzHugh-Nagumo oscillators in the bistable regime. A new type of chimera patterns has been found in the noise-free network and when isolated elements do not oscillate. The region of existence of these structures has been explored when the coupling range and the coupling strength between the network elements are varied.

Climate Controls on Tree Growth in the Western Mediterranean

NASA Technical Reports Server (NTRS)

Touchan, Ramzi; Anchukaitis, Kevin J.; Meko, David M.; Kerchouche, Dalila; Slimani, Said; Ilmen, Rachid; Hasnaoui, Fouad; Guibal, Frederic; Canarerim Hesys Hykui; Sanchez-Salguero, Raul;

Analysis of Optimal Jitter Buffer Size for VoIP QoS under WiMAX Power-Saving Mode

NASA Astrophysics Data System (ADS)

Kim, Hyungsuk; Kim, Taehyoun

VoIP service is expected as one of the key applications of Mobile WiMAX, but the speech quality of VoIP service often suffers deterioration due to the fluctuating transmission delay called jitter. This is commonly ameliorated by a de-jitter buffer, and we aim to find the optimal size of de-jitter buffer to achieve speech quality comparable to PSTN. We developed a new model of the packet drops at the de-jitter buffer and the end-to-end packet delay which takes account of the additional delay introduced by the WiMAX power-saving mode. Using our model, we analyzed the optimal size of the de-jitter buffer for various network parameters, and showed that the results obtained by analysis accord with simulation results.

Using simple agent-based modeling to inform and enhance neighborhood walkability

PubMed Central

2013-01-01

Background Pedestrian-friendly neighborhoods with proximal destinations and services encourage walking and decrease car dependence, thereby contributing to more active and healthier communities. Proximity to key destinations and services is an important aspect of the urban design decision making process, particularly in areas adopting a transit-oriented development (TOD) approach to urban planning, whereby densification occurs within walking distance of transit nodes. Modeling destination access within neighborhoods has been limited to circular catchment buffers or more sophisticated network-buffers generated using geoprocessing routines within geographical information systems (GIS). Both circular and network-buffer catchment methods are problematic. Circular catchment models do not account for street networks, thus do not allow exploratory ‘what-if’ scenario modeling; and network-buffering functionality typically exists within proprietary GIS software, which can be costly and requires a high level of expertise to operate. Methods This study sought to overcome these limitations by developing an open-source simple agent-based walkable catchment tool that can be used by researchers, urban designers, planners, and policy makers to test scenarios for improving neighborhood walkable catchments. A simplified version of an agent-based model was ported to a vector-based open source GIS web tool using data derived from the Australian Urban Research Infrastructure Network (AURIN). The tool was developed and tested with end-user stakeholder working group input. Results The resulting model has proven to be effective and flexible, allowing stakeholders to assess and optimize the walkability of neighborhood catchments around actual or potential nodes of interest (e.g., schools, public transport stops). Users can derive a range of metrics to compare different scenarios modeled. These include: catchment area versus circular buffer ratios; mean number of streets crossed; and modeling of different walking speeds and wait time at intersections. Conclusions The tool has the capacity to influence planning and public health advocacy and practice, and by using open-access source software, it is available for use locally and internationally. There is also scope to extend this version of the tool from a simple to a complex model, which includes agents (i.e., simulated pedestrians) ‘learning’ and incorporating other environmental attributes that enhance walkability (e.g., residential density, mixed land use, traffic volume). PMID:24330721

Enzyme localization, crowding, and buffers collectively modulate diffusion-influenced signal transduction: Insights from continuum diffusion modeling

PubMed Central

Kekenes-Huskey, Peter M.; Eun, Changsun; McCammon, J. A.

2015-01-01

Biochemical reaction networks consisting of coupled enzymes connect substrate signaling events with biological function. Substrates involved in these reactions can be strongly influenced by diffusion “barriers” arising from impenetrable cellular structures and macromolecules, as well as interactions with biomolecules, especially within crowded environments. For diffusion-influenced reactions, the spatial organization of diffusion barriers arising from intracellular structures, non-specific crowders, and specific-binders (buffers) strongly controls the temporal and spatial reaction kinetics. In this study, we use two prototypical biochemical reactions, a Goodwin oscillator, and a reaction with a periodic source/sink term to examine how a diffusion barrier that partitions substrates controls reaction behavior. Namely, we examine how conditions representative of a densely packed cytosol, including reduced accessible volume fraction, non-specific interactions, and buffers, impede diffusion over nanometer length-scales. We find that diffusion barriers can modulate the frequencies and amplitudes of coupled diffusion-influenced reaction networks, as well as give rise to “compartments” of decoupled reactant populations. These effects appear to be intensified in the presence of buffers localized to the diffusion barrier. These findings have strong implications for the role of the cellular environment in tuning the dynamics of signaling pathways. PMID:26342355

Improvements in multimedia data buffering using master/slave architecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheikh, S.; Ganesan, R.

1996-12-31

Advances in the networking technology and multimedia technology has necessitated a need for multimedia servers to be robust and reliable. Existing solutions have direct limitations such as I/O bottleneck and reliability of data retrieval. The system can store the stream of incoming data if enough buffer space is available or the mass storage is clearing the buffer data faster than queue input. A single buffer queue is not sufficient to handle the large frames. Queue sizes are normally several megabytes in length and thus in turn will introduce a state of overflow. The system should also keep track of themore » rewind, fast forwarding, and pause requests, otherwise queue management will become intricate. In this paper, we present a master/slave (server that is designated to monitor the workflow of the complete system. This server holds every other information of slaves by maintaining a dynamic table. It also controls the workload on each of the systems by redistributing request to others or handles the request by itself) approach which will overcome the limitations of today`s storage and also satisfy tomorrow`s storage needs. This approach will maintain the system reliability and yield faster response by using more storage units in parallel. A network of master/slave can handle many requests and synchronize them at all times. Using dedicated CPU and a common pool of queues we explain how queues can be controlled and buffer overflow can be avoided. We propose a layered approach to the buffering problem and provide a read-ahead solution to ensure continuous storage and retrieval of multimedia data.« less

Enhanced just-in-time plus protocol for optical burst switching networks

NASA Astrophysics Data System (ADS)

Rodrigues, Joel J. P. C.; Gregório, José M. B.; Vasilakos, Athanasios V.

2010-07-01

We propose a new one-way resource reservation protocol for optical burst switching (OBS) networks, called Enhanced Just-in-Time Plus (E-JIT+). The protocol is described in detail, and its formal specification is presented, following an extended finite state machine approach. The performance evaluation of E-JIT+ is analyzed in comparison with other proposed OBS protocols (JIT+ and E-JIT) for the following network topologies: rings; degree-two, degree-three, and degree-four chordal rings; mesh-torus; NSFNET; ARPANET; FCCN-NET; and the European Optical Network. We evaluate and compare the performance of the different protocols in terms of burst loss probability, taking into account the most important OBS network parameters. It was shown that E-JIT+ performs better than available one-way resource reservation protocols for all the evaluated network topologies. Moreover, the scalability of E-JIT+ was observed, and when the network traffic increases, the burst loss probability also increases, leading to a worse network performance.

Dependency links can hinder the evolution of cooperation in the prisoner's dilemma game on lattices and networks.

PubMed

Wang, Xuwen; Nie, Sen; Wang, Binghong

2015-01-01

Networks with dependency links are more vulnerable when facing the attacks. Recent research also has demonstrated that the interdependent groups support the spreading of cooperation. We study the prisoner's dilemma games on spatial networks with dependency links, in which a fraction of individual pairs is selected to depend on each other. The dependency individuals can gain an extra payoff whose value is between the payoff of mutual cooperation and the value of temptation to defect. Thus, this mechanism reflects that the dependency relation is stronger than the relation of ordinary mutual cooperation, but it is not large enough to cause the defection of the dependency pair. We show that the dependence of individuals hinders, promotes and never affects the cooperation on regular ring networks, square lattice, random and scale-free networks, respectively. The results for the square lattice and regular ring networks are demonstrated by the pair approximation.

Effects of time delays on stability and Hopf bifurcation in a fractional ring-structured network with arbitrary neurons

NASA Astrophysics Data System (ADS)

Huang, Chengdai; Cao, Jinde; Xiao, Min; Alsaedi, Ahmed; Hayat, Tasawar

2018-04-01

This paper is comprehensively concerned with the dynamics of a class of high-dimension fractional ring-structured neural networks with multiple time delays. Based on the associated characteristic equation, the sum of time delays is regarded as the bifurcation parameter, and some explicit conditions for describing delay-dependent stability and emergence of Hopf bifurcation of such networks are derived. It reveals that the stability and bifurcation heavily relies on the sum of time delays for the proposed networks, and the stability performance of such networks can be markedly improved by selecting carefully the sum of time delays. Moreover, it is further displayed that both the order and the number of neurons can extremely influence the stability and bifurcation of such networks. The obtained criteria enormously generalize and improve the existing work. Finally, numerical examples are presented to verify the efficiency of the theoretical results.

A Lossless Network for Data Acquisition

NASA Astrophysics Data System (ADS)

Jereczek, Grzegorz; Lehmann Miotto, Giovanna; Malone, David; Walukiewicz, Miroslaw

2017-06-01

The bursty many-to-one communication pattern, typical for data acquisition systems, is particularly demanding for commodity TCP/IP and Ethernet technologies. We expand the study of lossless switching in software running on commercial off-the-shelf servers, using the ATLAS experiment as a case study. In this paper, we extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism for data acquisition. We compare the performance under heavy congestion on typical Ethernet switches to a commodity server acting as a switch. Our results indicate that software switches with large buffers perform significantly better. Next, we evaluate the scalability of the system when building a larger topology of interconnected software switches, exploiting the integration with software-defined networking technologies. We build an IP-only leaf-spine network consisting of eight software switches running on distinct physical servers as a demonstrator.

Optofluidic ring resonator sensor for sensitive label-free detection of breast cancer antigen CA15-3 in human serum

NASA Astrophysics Data System (ADS)

Zhu, Hongying; Dale, Paul S.; Fan, Xudong

2009-05-01

Breast cancer is the most frequently diagnosed malignancy in women worldwide. Because of its great impact on society, a lot of research funding has been used to develop novel detection tools for aiding breast cancer diagnosis and prognosis. In this work, we demonstrated a simple, fast, and sensitive detection of circulating breast cancer biomarker CA15-3 with opto-fluidic ring resonator (OFRR) sensors. The OFRR sensor employs a thin-walled capillary with wall thickness less than 4 μm. The circular cross section of the capillary forms the optical ring resonator, in which the light circulates in the form of whispering gallery modes (WGMs). The capillary wall is thin enough that the evanescent field of the WGM extends into the capillary core and responds to refractive index changes in the capillary core or close to its interior surface. The WGM spectral position will change when the biomolecules bind to the surface, yielding quantitative and kinetic information about the biomolecule interaction. Here, the direct immunoassay method was employed for the detection of CA15-3 antigen without any signal amplification steps. The sensor performance in both PBS buffer and human serum were investigated, respectively. The experimental detection limit was 5 units/mL in PBS buffer and 30 units/mL for CA15-3 spiked in serum, both of which satisfied clinical diagnosis requirements. The potential use of the OFRR as the point-of-care device for breast cancer detection was tested by measuring the CA15-3 level in blood samples collected from stage IV breast cancer patients and the results were compared with standard clinical test.

Effecting a broadcast with an allreduce operation on a parallel computer

DOEpatents

Almasi, Gheorghe; Archer, Charles J.; Ratterman, Joseph D.; Smith, Brian E.

2010-11-02

A parallel computer comprises a plurality of compute nodes organized into at least one operational group for collective parallel operations. Each compute node is assigned a unique rank and is coupled for data communications through a global combining network. One compute node is assigned to be a logical root. A send buffer and a receive buffer is configured. Each element of a contribution of the logical root in the send buffer is contributed. One or more zeros corresponding to a size of the element are injected. An allreduce operation with a bitwise OR using the element and the injected zeros is performed. And the result for the allreduce operation is determined and stored in each receive buffer.

Optical burst switching for the next generation Optical Internet

NASA Astrophysics Data System (ADS)

Yoo, Myungsik

2000-11-01

In recent years, Internet Protocol (IP) over Wavelength Division Multiplexing (WDM) networks for the next generation Internet (or the so-called Optical Internet) have received enormous attention. There are two main drivers for an Optical Internet. One is the explosion of Internet traffic, which seems to keep growing exponentially. The other driver is the rapid advance in the WDM optical networking technology. In this study, key issues in the optical (WDM) layer will be investigated. As a novel switching paradigm for Optical Internet, Optical Burst Switching (OBS) is discussed. By leveraging the attractive properties of optical communications and at the same time, taking into account its limitations, OBS can combine the best of optical circuit-switching and packet/cell switching. The general concept of JET-based OBS protocol is described, including offset time and delayed reservation. In the next generation Optical Internet, one must address how to support Quality of Service (QoS) at the WDM layer since current IP provides only best effort services. The offset-time- based QoS scheme is proposed as a way of supporting QoS at the WDM layer. Unlike existing QoS schemes, offset- time-based QoS scheme does not mandate the use of buffer to differentiate services. For the bufferless WDM switch, the performance of offset- time-based QoS scheme is evaluated in term of blocking probability. In addition, the extra offset time required for class isolation is quantified and the theoretical bounds on blocking probability are analyzed. The offset-time-based scheme is applied to WDM switch with limited fiber delay line (FDL) buffer. We evaluate the effect of having a FDL buffer on the QoS performance of the offset-time-based scheme in terms of the loss probability and queuing delay of bursts. Finally, in order to dimension the network resources in Optical Internet backbone networks, the performance of the offset-time-based QoS scheme is evaluated for the multi-hop case. In particular, we consider very high performance Backbone Network Service (vBNS) backbone network. Various policies such as drop, retransmission, deflection routing and buffering are considered for performance evaluation. The performance results obtained under these policies are compared to decide the most efficient policy for the WDM backbone network.

Connectivity among sinkholes and complex networks: The case of Ring of Cenotes in northwest Yucatan, Mexico

NASA Astrophysics Data System (ADS)

Gomez-Nicolas, Mariana; Rebolledo-Vieyra, Mario; Huerta-Quintanilla, Rodrigo; Canto-Lugo, Efrain

2014-05-01

A 180-km-diameter semicircular alignment of abundant karst sinkholes (locally known as cenotes) in northwestern Yucatán, México, coincides approximately with a concentric ring of the buried Chicxulub structure, a circular feature manifested in Cretaceous and older rocks, that has been identified as the product of the impact of a meteorite. The secondary permeability generated by the fracturing and faulting of the sedimentary sequence in the Chicxulub impact, has favored the karstification process and hence the development of genuine underground rivers that carry water from the continent to the sea. The study of the structure and morphology of the crater has allowed researchers to understand the key role of the crater in the Yucatán hydrogeology. It is generally accepted that the Ring of Cenotes, produced by the gravitational deformation of the Tertiary sedimentary sequence within the crater, controls the groundwater in northern Yucatán. However, today there is not solid evidence about the connectivity among cenotes, which is important because if established, public policies could be designed to manage sanitary infrastructure, septic control, regulation of agricultural and industrial activities and the protection of water that has not been compromised by anthropogenic pollution. All these directly affect more than half a million people whose main source of drinking water lies in the aquifer. In this contribution we investigated a set of 16 cenotes located in the vicinity of a gravimetric anomaly of Chicxulub crater ring, using complex networks to model the interconnectivity among them. Data from a geoelectrical tomography survey, collected with SuperSting R1/IP equipment, with multi-electrodes (72 electrodes), in a dipole-dipole configuration was used as input of our model. Since the total number of cenotes on the ring structure amounts to about 2000, the application of graph theoretic algorithms and Monte Carlo simulation to efficiently investigate network properties is proposed. We created a digital network model representing the observation network topology.

Photophysical Characterization and BSA Interaction of Direct Ring Carboxy Functionalized Symmetrical squaraine Dyes

NASA Astrophysics Data System (ADS)

Saikiran, Maryala; Pandey, Shyam S.; Hayase, Shuzi; Kato, Tamaki

2017-11-01

A series of far-red sensitive symmetrical squaraine dyes bearing direct -COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations. These symmetrical squaraine dyes were then subjected to investigate their interaction with bovine serum albumin (BSA) in Phosphate buffer solutions. All the squaraine dyes under investigation exhibit intense and sharp optical absorption mainly in the far-red wavelength region from 550 nm -700 nm having very high molar extinction coefficients from 1.3 × 105 dm3.mol-1.cm-1. A very small Stokes shift of 10-17 nm indicates the rigid conformational structure of squaraine chromophore. Interaction of these dyes with BSA leads to not only enhanced emission intensity but also bathochromically shifted absorption maximum due to formation of dye-BSA conjugate. These dyes bind strongly with BSA having about an order of magnitude higher binding constant as compared to the reported squaraine dyes. Amongst the symmetrical squaraine dyes investigated in this work one bearing substituents like trifluorobutyl as alkyl chain at N-position of indole ring and carboxylic acid on benzene ring at the terminal (SQ-26) exhibited highest association with the BSA having very high binding constant 8.01 × 106 M-1.

Novel inclusion complex of ibuprofen tromethamine with cyclodextrins: physico-chemical characterization.

PubMed

Al Omari, Mahmoud M; Daraghmeh, Nidal H; El-Barghouthi, Musa I; Zughul, Mohammad B; Chowdhry, Babur Z; Leharne, Stephen A; Badwan, Adnan A

2009-10-15

Guest-host interactions of ibuprofen tromethamine salt (Ibu.T) with native and modified cyclodextrins (CyDs) have been investigated using several techniques, namely phase solubility diagrams (PSDs), proton nuclear magnetic resonance ((1)H NMR), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffractometry (XRPD), scanning-electron microscopy (SEM) and molecular mechanics (MM). From the analysis of PSD data (A(L)-type) it is concluded that the anionic tromethamine salt of ibuprofen (pK(a)=4.55) forms 1:1 soluble complexes with all CyDs investigated in buffered water at pH 7.0, while the neutral form of Ibu forms an insoluble complex with beta-CyD (B(S)-type) in buffered water at pH 2.0. Ibu.T has a lower tendency to complex with beta-CyD (K(11)=58 M(-1) at pH 7.0) compared with the neutral Ibu (K(11)=4200 M(-1)) in water. Complex formation of Ibu.T with beta-CyD (DeltaG(o)=-20.4 kJ/mol) is enthalpy driven (DeltaH(o)=-22.9 kJ/mol) and is accompanied by a small unfavorable entropy (DeltaS(o)=-8.4 J/mol K) change. (1)H NMR studies and MM computations revealed that, on complexation, the hydrophobic central benzene ring of Ibu.T and part of the isobutyl group reside within the beta-CyD cavity leaving the peripheral groups (carboxylate, tromethamine and methyl groups) located near the hydroxyl group networks at either rim of beta-CyD. PSD, (1)H NMR, DSC, FT-IR, XRPD, SEM and MM studies confirmed the formation of Ibu.T/beta-CyD inclusion complex in solution and the solid state.

Data Access Based on a Guide Map of the Underwater Wireless Sensor Network

PubMed Central

Wei, Zhengxian; Song, Min; Yin, Guisheng; Wang, Hongbin; Cheng, Albert M. K.

2017-01-01

Underwater wireless sensor networks (UWSNs) represent an area of increasing research interest, as data storage, discovery, and query of UWSNs are always challenging issues. In this paper, a data access based on a guide map (DAGM) method is proposed for UWSNs. In DAGM, the metadata describes the abstracts of data content and the storage location. The center ring is composed of nodes according to the shortest average data query path in the network in order to store the metadata, and the data guide map organizes, diffuses and synchronizes the metadata in the center ring, providing the most time-saving and energy-efficient data query service for the user. For this method, firstly the data is stored in the UWSN. The storage node is determined, the data is transmitted from the sensor node (data generation source) to the storage node, and the metadata is generated for it. Then, the metadata is sent to the center ring node that is the nearest to the storage node and the data guide map organizes the metadata, diffusing and synchronizing it to the other center ring nodes. Finally, when there is query data in any user node, the data guide map will select a center ring node nearest to the user to process the query sentence, and based on the shortest transmission delay and lowest energy consumption, data transmission routing is generated according to the storage location abstract in the metadata. Hence, specific application data transmission from the storage node to the user is completed. The simulation results demonstrate that DAGM has advantages with respect to data access time and network energy consumption. PMID:29039757

Data Access Based on a Guide Map of the Underwater Wireless Sensor Network.

PubMed

Wei, Zhengxian; Song, Min; Yin, Guisheng; Song, Houbing; Wang, Hongbin; Ma, Xuefei; Cheng, Albert M K

2017-10-17

Underwater wireless sensor networks (UWSNs) represent an area of increasing research interest, as data storage, discovery, and query of UWSNs are always challenging issues. In this paper, a data access based on a guide map (DAGM) method is proposed for UWSNs. In DAGM, the metadata describes the abstracts of data content and the storage location. The center ring is composed of nodes according to the shortest average data query path in the network in order to store the metadata, and the data guide map organizes, diffuses and synchronizes the metadata in the center ring, providing the most time-saving and energy-efficient data query service for the user. For this method, firstly the data is stored in the UWSN. The storage node is determined, the data is transmitted from the sensor node (data generation source) to the storage node, and the metadata is generated for it. Then, the metadata is sent to the center ring node that is the nearest to the storage node and the data guide map organizes the metadata, diffusing and synchronizing it to the other center ring nodes. Finally, when there is query data in any user node, the data guide map will select a center ring node nearest to the user to process the query sentence, and based on the shortest transmission delay and lowest energy consumption, data transmission routing is generated according to the storage location abstract in the metadata. Hence, specific application data transmission from the storage node to the user is completed. The simulation results demonstrate that DAGM has advantages with respect to data access time and network energy consumption.

On buffer overflow duration in a finite-capacity queueing system with multiple vacation policy

NASA Astrophysics Data System (ADS)

Kempa, Wojciech M.

2017-12-01

A finite-buffer queueing system with Poisson arrivals and generally distributed processing times, operating under multiple vacation policy, is considered. Each time when the system becomes empty, the service station takes successive independent and identically distributed vacation periods, until, at the completion epoch of one of them, at least one job waiting for service is detected in the buffer. Applying analytical approach based on the idea of embedded Markov chain, integral equations and linear algebra, the compact-form representation for the cumulative distribution function (CDF for short) of the first buffer overflow duration is found. Hence, the formula for the CDF of next such periods is obtained. Moreover, probability distributions of the number of job losses in successive buffer overflow periods are found. The considered queueing system can be efficienly applied in modelling energy saving mechanisms in wireless network communication.

The Dark Side of Saturn's Gravity

NASA Astrophysics Data System (ADS)

Iess, L.; Racioppa, P.; Durante, D.; Mariani, M., Jr.; Anabtawi, A.; Armstrong, J. W.; Gomez Casajus, L.; Tortora, P.; Zannoni, M.

2017-12-01

On July 19, 2017 the Cassini spacecraft successfully completed its sixth and last pericenter pass devoted to the investigation of Saturn's interior structure and rings. During each pass the spacecraft was tracked for about 24 hours by the antennas of NASA's Deep Space Network and ESA's ESTRACK network, providing high quality measurements of the spacecraft range rate. We report on a preliminary estimate of Saturn's gravity field and ring mass inferred from range rate observables, and discuss the surprising features of our findings.

Defense Data Network/TOPS-20 Tutorial. An Interative Computer Program.

DTIC Science & Technology

1985-12-01

33 XI. ELECTRONIC MAIL HOST ( EMH )-------------------------- 34 XII. EMACS...contents of text buffer to a file X EXCHANGE , used to search for and replace text Z ZAP, puts your entire file into the print buffer 23 - -° SWITCH...prompt USC-ISIE.ARPA> Sample foreign host command level prompt FTP COMMAND LEVEL COMMANDS COMMAND USE(S) FTP Invokes the FTP protocol CONNECT Connects

Development of buffer layer structure for epitaxial growth of (100)/(001)Pb(Zr,Ti)O3-based thin film on (111)Si wafer

NASA Astrophysics Data System (ADS)

Hayasaka, Takeshi; Yoshida, Shinya; Tanaka, Shuji

2017-07-01

This paper reports on the development of a novel buffer layer structure, (100)SrRuO3/(100)LaNiO3/(111)Pt/(111)CeO2, for the epitaxial growth of a (100)/(001)-oriented Pb(Zr,Ti)O3 (PZT)-based thin film on a (111)Si wafer. (111)Pt and (111)CeO2 were epitaxially grown on (111)Si straightforwardly. Then, the crystal orientation was forcibly changed from (111) to (100) at the LaNiO3 layer owing to its strong (100)-self-orientation property, which enabled the cube-on-cube epitaxial growth of the subsequent (100)SrRuO3 layer and preferentially (100)/(001)-oriented PZT-based thin film. The PZT-based epitaxial thin films were comprehensively characterized in terms of the crystallinity, in-plane epitaxial relationships, piezoelectricity, and so forth. This buffer layer structure for the epitaxial growth of PZT can be applied to piezoelectric micro-electro-mechanical systems (MEMS) vibrating ring gyroscopes.

Rapid cell-free forward engineering of novel genetic ring oscillators

PubMed Central

Niederholtmeyer, Henrike; Sun, Zachary Z; Hori, Yutaka; Yeung, Enoch; Verpoorte, Amanda; Murray, Richard M; Maerkl, Sebastian J

2015-01-01

While complex dynamic biological networks control gene expression in all living organisms, the forward engineering of comparable synthetic networks remains challenging. The current paradigm of characterizing synthetic networks in cells results in lengthy design-build-test cycles, minimal data collection, and poor quantitative characterization. Cell-free systems are appealing alternative environments, but it remains questionable whether biological networks behave similarly in cell-free systems and in cells. We characterized in a cell-free system the ‘repressilator’, a three-node synthetic oscillator. We then engineered novel three, four, and five-gene ring architectures, from characterization of circuit components to rapid analysis of complete networks. When implemented in cells, our novel 3-node networks produced population-wide oscillations and 95% of 5-node oscillator cells oscillated for up to 72 hr. Oscillation periods in cells matched the cell-free system results for all networks tested. An alternate forward engineering paradigm using cell-free systems can thus accurately capture cellular behavior. DOI: http://dx.doi.org/10.7554/eLife.09771.001 PMID:26430766

Nonequilibrium landscape theory of neural networks.

PubMed

Yan, Han; Zhao, Lei; Hu, Liang; Wang, Xidi; Wang, Erkang; Wang, Jin

2013-11-05

The brain map project aims to map out the neuron connections of the human brain. Even with all of the wirings mapped out, the global and physical understandings of the function and behavior are still challenging. Hopfield quantified the learning and memory process of symmetrically connected neural networks globally through equilibrium energy. The energy basins of attractions represent memories, and the memory retrieval dynamics is determined by the energy gradient. However, the realistic neural networks are asymmetrically connected, and oscillations cannot emerge from symmetric neural networks. Here, we developed a nonequilibrium landscape-flux theory for realistic asymmetrically connected neural networks. We uncovered the underlying potential landscape and the associated Lyapunov function for quantifying the global stability and function. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. We applied our theory to rapid-eye movement sleep cycle. We identified the key regulation factors for function through global sensitivity analysis of landscape topography against wirings, which are in good agreements with experiments.

Nonequilibrium landscape theory of neural networks

PubMed Central

Yan, Han; Zhao, Lei; Hu, Liang; Wang, Xidi; Wang, Erkang; Wang, Jin

2013-01-01

The brain map project aims to map out the neuron connections of the human brain. Even with all of the wirings mapped out, the global and physical understandings of the function and behavior are still challenging. Hopfield quantified the learning and memory process of symmetrically connected neural networks globally through equilibrium energy. The energy basins of attractions represent memories, and the memory retrieval dynamics is determined by the energy gradient. However, the realistic neural networks are asymmetrically connected, and oscillations cannot emerge from symmetric neural networks. Here, we developed a nonequilibrium landscape–flux theory for realistic asymmetrically connected neural networks. We uncovered the underlying potential landscape and the associated Lyapunov function for quantifying the global stability and function. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. We applied our theory to rapid-eye movement sleep cycle. We identified the key regulation factors for function through global sensitivity analysis of landscape topography against wirings, which are in good agreements with experiments. PMID:24145451

Stress, Social Support and Problem Drinking among Women in Poverty

PubMed Central

Mulia, Nina; Schmidt, Laura; Bond, Jason; Jacobs, Laurie; Korcha, Rachael

2009-01-01

Aims Prior studies find that stress contributes to problem drinking while social support can buffer its effects. However, these studies are largely confined to middle class and general populations. We extend what is known by examining how the unique stressors and forms of social support experienced by women in poverty impact alcohol problems over a 4-year time period. Design and Participants This prospective study used GEE transition modeling and 4 annual waves of survey data from 392 American mothers receiving Temporary Assistance for Needy Families (TANF) in a large Northern California county. Measurements We examined the effects of neighborhood disorder, stressful life events and economic hardship on psychological distress and problem drinking over time, and whether social support moderated these relationships for women in poverty. Findings Neighborhood disorder and stressful life events significantly increased the risk for problem drinking, largely through their effect on psychological distress. We found little evidence, however, that social support buffers poor women from the effects of these stressors. Conclusions Women in poverty are exposed to severe, chronic stressors within their communities and immediate social networks which increase vulnerability to psychological distress and problem drinking. The finding that social support does not buffer stress among these women may reflect their high level of exposure to stressors, as well as the hardships and scarce resources within their networks. If the “private safety net” of the social network fails to provide a strong buffer, more effective environmental interventions that reduce exposure to stressors may be needed to prevent alcohol problems in poor women’s lives. PMID:18855817

Layer-based buffer aware rate adaptation design for SHVC video streaming

NASA Astrophysics Data System (ADS)

Gudumasu, Srinivas; Hamza, Ahmed; Asbun, Eduardo; He, Yong; Ye, Yan

2016-09-01

This paper proposes a layer based buffer aware rate adaptation design which is able to avoid abrupt video quality fluctuation, reduce re-buffering latency and improve bandwidth utilization when compared to a conventional simulcast based adaptive streaming system. The proposed adaptation design schedules DASH segment requests based on the estimated bandwidth, dependencies among video layers and layer buffer fullness. Scalable HEVC video coding is the latest state-of-art video coding technique that can alleviate various issues caused by simulcast based adaptive video streaming. With scalable coded video streams, the video is encoded once into a number of layers representing different qualities and/or resolutions: a base layer (BL) and one or more enhancement layers (EL), each incrementally enhancing the quality of the lower layers. Such layer based coding structure allows fine granularity rate adaptation for the video streaming applications. Two video streaming use cases are presented in this paper. The first use case is to stream HD SHVC video over a wireless network where available bandwidth varies, and the performance comparison between proposed layer-based streaming approach and conventional simulcast streaming approach is provided. The second use case is to stream 4K/UHD SHVC video over a hybrid access network that consists of a 5G millimeter wave high-speed wireless link and a conventional wired or WiFi network. The simulation results verify that the proposed layer based rate adaptation approach is able to utilize the bandwidth more efficiently. As a result, a more consistent viewing experience with higher quality video content and minimal video quality fluctuations can be presented to the user.

Stress, social support and problem drinking among women in poverty.

PubMed

Mulia, Nina; Schmidt, Laura; Bond, Jason; Jacobs, Laurie; Korcha, Rachael

2008-08-01

Previous studies have found that stress contributes to problem drinking, while social support can buffer its effects. However, these studies are confined largely to middle-class and general populations. We extend what is known by examining how the unique stressors and forms of social support experienced by women in poverty impact alcohol problems over a 4-year time-period. This prospective study used generalized estimating equations (GEE) transition modeling and four annual waves of survey data from 392 American mothers receiving Temporary Assistance for Needy Families (TANF) in a large Northern California county. We examined the effects of neighborhood disorder, stressful life events and economic hardship on psychological distress and problem drinking over time, and whether social support moderated these relationships for women in poverty. Neighborhood disorder and stressful life events increased significantly the risk for problem drinking, largely through their effect on psychological distress. We found little evidence, however, that social support buffers poor women from the effects of these stressors. Women in poverty are exposed to severe, chronic stressors within their communities and immediate social networks which increase vulnerability to psychological distress and problem drinking. The finding that social support does not buffer stress among these women may reflect their high level of exposure to stressors, as well as the hardships and scarce resources within their networks. If the 'private safety net' of the social network fails to provide a strong buffer, more effective environmental interventions that reduce exposure to stressors may be needed to prevent alcohol problems in poor women's lives.

A spectroscopic study of the hydrogen bonding and pi-pi stacking interactions of harmane with quinoline.

PubMed

Balón, M; Guardado, P; Muñoz, M A; Carmona, C

1998-01-01

A spectroscopic (UV-vis, Fourier transform IR, steady state, and time-resolved fluorescence) study of the interactions of the ground and excited singlet states of harmane (1-methyl-9H-pyrido/3,4-b/indole) with quinoline has been carried out in cyclohexane, toluene, and buffered pH=8.7 aqueous solutions. To analyze how the number of rings in the substrate influences these interactions, pyridine and phenanthridine have also been included in this study. In cyclohexane and toluene 1:1 stoichiometric hydrogen-bonded complexes are formed in both the ground and the excited singlet states. As the number of rings of the benzopyridines and the solvent polarity increase hydrogen-bonding interactions weaken and pi-pi van der Waals interactions become apparent.

Degradation mechanisms of Ti/Al/Ni/Au-based Ohmic contacts on AlGaN/GaN HEMTs

DOE PAGES

Hwang, Ya-Hsi; Ahn, Shihyun; Dong, Chen; ...

2015-04-27

We investigated the degradation mechanism of Ti/Al/Ni/Au-based Ohmic metallization on AlGaN/GaN high electron mobility transistors upon exposure to buffer oxide etchant (BOE). The major effect of BOE on the Ohmic metal was an increase of sheet resistance from 2.89 to 3.69 Ω/ₜafter 3 min BOE treatment. The alloyed Ohmic metallization consisted 3–5 μm Ni-Al alloy islands surrounded by Au-Al alloy-rings. The morphology of both the islands and ring areas became flatter after BOE etching. Lastly, we used energy dispersive x-ray analysis and Auger electron microscopy to analyze the compositions and metal distributions in the metal alloys prior to and aftermore » BOE exposure.« less

Chimera patterns in two-dimensional networks of coupled neurons.

PubMed

Schmidt, Alexander; Kasimatis, Theodoros; Hizanidis, Johanne; Provata, Astero; Hövel, Philipp

2017-03-01

We discuss synchronization patterns in networks of FitzHugh-Nagumo and leaky integrate-and-fire oscillators coupled in a two-dimensional toroidal geometry. A common feature between the two models is the presence of fast and slow dynamics, a typical characteristic of neurons. Earlier studies have demonstrated that both models when coupled nonlocally in one-dimensional ring networks produce chimera states for a large range of parameter values. In this study, we give evidence of a plethora of two-dimensional chimera patterns of various shapes, including spots, rings, stripes, and grids, observed in both models, as well as additional patterns found mainly in the FitzHugh-Nagumo system. Both systems exhibit multistability: For the same parameter values, different initial conditions give rise to different dynamical states. Transitions occur between various patterns when the parameters (coupling range, coupling strength, refractory period, and coupling phase) are varied. Many patterns observed in the two models follow similar rules. For example, the diameter of the rings grows linearly with the coupling radius.

Chimera patterns in two-dimensional networks of coupled neurons

NASA Astrophysics Data System (ADS)

Schmidt, Alexander; Kasimatis, Theodoros; Hizanidis, Johanne; Provata, Astero; Hövel, Philipp

2017-03-01

We discuss synchronization patterns in networks of FitzHugh-Nagumo and leaky integrate-and-fire oscillators coupled in a two-dimensional toroidal geometry. A common feature between the two models is the presence of fast and slow dynamics, a typical characteristic of neurons. Earlier studies have demonstrated that both models when coupled nonlocally in one-dimensional ring networks produce chimera states for a large range of parameter values. In this study, we give evidence of a plethora of two-dimensional chimera patterns of various shapes, including spots, rings, stripes, and grids, observed in both models, as well as additional patterns found mainly in the FitzHugh-Nagumo system. Both systems exhibit multistability: For the same parameter values, different initial conditions give rise to different dynamical states. Transitions occur between various patterns when the parameters (coupling range, coupling strength, refractory period, and coupling phase) are varied. Many patterns observed in the two models follow similar rules. For example, the diameter of the rings grows linearly with the coupling radius.

Irregular synchronous activity in stochastically-coupled networks of integrate-and-fire neurons.

PubMed

Lin, J K; Pawelzik, K; Ernst, U; Sejnowski, T J

1998-08-01

We investigate the spatial and temporal aspects of firing patterns in a network of integrate-and-fire neurons arranged in a one-dimensional ring topology. The coupling is stochastic and shaped like a Mexican hat with local excitation and lateral inhibition. With perfect precision in the couplings, the attractors of activity in the network occur at every position in the ring. Inhomogeneities in the coupling break the translational invariance of localized attractors and lead to synchronization within highly active as well as weakly active clusters. The interspike interval variability is high, consistent with recent observations of spike time distributions in visual cortex. The robustness of our results is demonstrated with more realistic simulations on a network of McGregor neurons which model conductance changes and after-hyperpolarization potassium currents.

Evaluating the role of river-floodplain connectivity in providing beneficial hydrologic services in mountain landscapes

NASA Astrophysics Data System (ADS)

Covino, T. P.; Wegener, P.; Weiss, T.; Wohl, E.; Rhoades, C.

2017-12-01

River networks of mountain landscapes tend to be dominated by steep, valley-confined channels that have limited floodplain area and low hydrologic buffering capacity. Interspersed between the narrow segments are wide, low-gradient segments where extensive floodplains, wetlands, and riparian areas can develop. Although they tend to be limited in their frequency relative to the narrow valley segments, the low-gradient, wide portions of mountain channel networks can be particularly important to hydrologic buffering and can be sites of high nutrient retention and ecosystem productivity. Hydrologic buffering along the wide valley segments is dependent on lateral hydrologic connectivity between the river and floodplain, however these connections have been increasingly severed as a result of various land and water management practices. We evaluated the role of river-floodplain connectivity in influencing water, dissolved organic carbon (DOC), and nutrient flux in river networks of the Colorado Rockies. We found that disconnected segments with limited floodplain/riparian area had limited buffering capacity, while connected segments exhibited variable source-sink dynamics as a function of flow. Specifically, connected segments were typically a sink for water, DOC, and nutrients during high flows, and subsequently became a source as flows decreased. Shifts in river-floodplain hydrologic connectivity across flows related to higher and more variable aquatic ecosystem metabolism rates along connected relative to disconnected segments. Our data suggest that lateral hydrologic connectivity in wide valleys can enhance hydrologic and biogeochemical buffering, and promote high rates of aquatic ecosystem metabolism. While hydrologic disconnection in one river-floodplain system is unlikely to influence water resources at larger scales, the cumulative effects of widespread disconnection may be substantial. Because intact river-floodplain (i.e., connected) systems provide numerous hydrologic and ecologic benefits, understanding the dynamics and cumulative effects of disconnection is an important step toward improved water resource and ecosystem management.

Socialising Health Burden Through Different Network Topologies: A Simulation Study.

PubMed

Peacock, Adrian; Cheung, Anthony; Kim, Peter; Poon, Simon K

2017-01-01

An aging population and the expectation of premium quality health services combined with the increasing economic burden of the healthcare system requires a paradigm shift toward patient oriented healthcare. The guardian angel theory described by Szolovits [1] explores the notion of enlisting patients as primary providers of information and motivation to patients with similar clinical history through social connections. In this study, an agent based model was developed to simulate to explore how individuals are affected through their levels of intrinsic positivity. Ring, point-to-point (paired buddy), and random networks were modelled, with individuals able to send messages to each other given their levels of variables positivity and motivation. Of the 3 modelled networks it is apparent that the ring network provides the most equal, collective improvement in positivity and motivation for all users. Further study into other network topologies should be undertaken in the future.

Predicting neural network firing pattern from phase resetting curve

NASA Astrophysics Data System (ADS)

Oprisan, Sorinel; Oprisan, Ana

2007-04-01

Autonomous neural networks called central pattern generators (CPG) are composed of endogenously bursting neurons and produce rhythmic activities, such as flying, swimming, walking, chewing, etc. Simplified CPGs for quadrupedal locomotion and swimming are modeled by a ring of neural oscillators such that the output of one oscillator constitutes the input for the subsequent neural oscillator. The phase response curve (PRC) theory discards the detailed conductance-based description of the component neurons of a network and reduces them to ``black boxes'' characterized by a transfer function, which tabulates the transient change in the intrinsic period of a neural oscillator subject to external stimuli. Based on open-loop PRC, we were able to successfully predict the phase-locked period and relative phase between neurons in a half-center network. We derived existence and stability criteria for heterogeneous ring neural networks that are in good agreement with experimental data.

Superframe Duration Allocation Schemes to Improve the Throughput of Cluster-Tree Wireless Sensor Networks

PubMed Central

Leão, Erico; Montez, Carlos; Moraes, Ricardo; Portugal, Paulo; Vasques, Francisco

2017-01-01

The use of Wireless Sensor Network (WSN) technologies is an attractive option to support wide-scale monitoring applications, such as the ones that can be found in precision agriculture, environmental monitoring and industrial automation. The IEEE 802.15.4/ZigBee cluster-tree topology is a suitable topology to build wide-scale WSNs. Despite some of its known advantages, including timing synchronisation and duty-cycle operation, cluster-tree networks may suffer from severe network congestion problems due to the convergecast pattern of its communication traffic. Therefore, the careful adjustment of transmission opportunities (superframe durations) allocated to the cluster-heads is an important research issue. This paper proposes a set of proportional Superframe Duration Allocation (SDA) schemes, based on well-defined protocol and timing models, and on the message load imposed by child nodes (Load-SDA scheme), or by number of descendant nodes (Nodes-SDA scheme) of each cluster-head. The underlying reasoning is to adequately allocate transmission opportunities (superframe durations) and parametrize buffer sizes, in order to improve the network throughput and avoid typical problems, such as: network congestion, high end-to-end communication delays and discarded messages due to buffer overflows. Simulation assessments show how proposed allocation schemes may clearly improve the operation of wide-scale cluster-tree networks. PMID:28134822

Multi-temporal monitoring of a regional riparian buffer network (>12,000 km) with LiDAR and photogrammetric point clouds.

PubMed

Michez, Adrien; Piégay, Hervé; Lejeune, Philippe; Claessens, Hugues

2017-11-01

Riparian buffers are of major concern for land and water resource managers despite their relatively low spatial coverage. In Europe, this concern has been acknowledged by different environmental directives which recommend multi-scale monitoring (from local to regional scales). Remote sensing methods could be a cost-effective alternative to field-based monitoring, to build replicable "wall-to-wall" monitoring strategies of large river networks and associated riparian buffers. The main goal of our study is to extract and analyze various parameters of the riparian buffers of up to 12,000 km of river in southern Belgium (Wallonia) from three-dimensional (3D) point clouds based on LiDAR and photogrammetric surveys to i) map riparian buffers parameters on different scales, ii) interpret the regional patterns of the riparian buffers and iii) propose new riparian buffer management indicators. We propose different strategies to synthesize and visualize relevant information at different spatial scales ranging from local (<10 km) to regional scale (>12,000 km). Our results showed that the selected parameters had a clear regional pattern. The reaches of Ardenne ecoregion have channels with the highest flow widths and shallowest depths. In contrast, the reaches of the Loam ecoregion have the narrowest and deepest flow channels. Regional variability in channel width and depth is used to locate management units potentially affected by human impact. Riparian forest of the Loam ecoregion is characterized by the lowest longitudinal continuity and mean tree height, underlining significant human disturbance. As the availability of 3D point clouds at the regional scale is constantly growing, our study proposes reproducible methods which can be integrated into regional monitoring by land managers. With LiDAR still being relatively expensive to acquire, the use of photogrammetric point clouds combined with LiDAR data is a cost-effective means to update the characterization of the riparian forest conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design and implementation of interface units for high speed fiber optics local area networks and broadband integrated services digital networks

NASA Technical Reports Server (NTRS)

Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph

1990-01-01

The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.

West Virginia forest industry transportation network analysis using GIS

Treesearch

Steven E. Harouff; Shawn T. Grushecky; Ben D. Spong

2008-01-01

To better understand and increase efficiency in delivery of harvested roundwood on West Virginia' roadways, a detailed network analysis using Geographic Information Systems (GIS) was conducted. Typical proximity-based analysis, which looks at straightline distances (buffers) around given features regardless of terrain and road characteristics, provides limited...

Isoscapes of tree-ring carbon-13 perform like meteorological networks in predicting regional precipitation patterns

NASA Astrophysics Data System (ADS)

del Castillo, Jorge; Aguilera, Mònica; Voltas, Jordi; Ferrio, Juan Pedro

2013-03-01

isotopes in tree rings provide climatic information with annual resolution dating back for centuries or even millennia. However, deriving spatially explicit climate models from isotope networks remains challenging. Here we propose a methodology to model regional precipitation from carbon isotope discrimination (Δ13C) in tree rings by (1) building regional spatial models of Δ13C (isoscapes) and (2) deriving precipitation maps from Δ13C-isoscapes, taking advantage of the response of Δ13C to precipitation in seasonally dry climates. As a case study, we modeled the spatial distribution of mean annual precipitation (MAP) in the northeastern Iberian Peninsula, a region with complex topography and climate (MAP = 303-1086 mm). We compiled wood Δ13C data for two Mediterranean species that exhibit complementary responses to seasonal precipitation (Pinus halepensis Mill., N = 38; Quercus ilex L.; N = 44; pooling period: 1975-2008). By combining multiple regression and geostatistical interpolation, we generated one Δ13 C-isoscape for each species. A spatial model of MAP was then built as the sum of two complementary maps of seasonal precipitation, each one derived from the corresponding Δ13C-isoscape (September-November from Q. ilex; December-August from P. halepensis). Our approach showed a predictive power for MAP (RMSE = 84 mm) nearly identical to that obtained by interpolating data directly from a similarly dense network of meteorological stations (RMSE = 80-83 mm, N = 65), being only outperformed when using a much denser meteorological network (RMSE = 56-57 mm, N = 340). This method offers new avenues for modeling spatial variability of past precipitation, exploiting the large amount of information currently available from tree-ring networks.

Executing a gather operation on a parallel computer

DOEpatents

Archer, Charles J [Rochester, MN; Ratterman, Joseph D [Rochester, MN

2012-03-20

Methods, apparatus, and computer program products are disclosed for executing a gather operation on a parallel computer according to embodiments of the present invention. Embodiments include configuring, by the logical root, a result buffer or the logical root, the result buffer having positions, each position corresponding to a ranked node in the operational group and for storing contribution data gathered from that ranked node. Embodiments also include repeatedly for each position in the result buffer: determining, by each compute node of an operational group, whether the current position in the result buffer corresponds with the rank of the compute node, if the current position in the result buffer corresponds with the rank of the compute node, contributing, by that compute node, the compute node's contribution data, if the current position in the result buffer does not correspond with the rank of the compute node, contributing, by that compute node, a value of zero for the contribution data, and storing, by the logical root in the current position in the result buffer, results of a bitwise OR operation of all the contribution data by all compute nodes of the operational group for the current position, the results received through the global combining network.

Local Area Networks: Part I.

ERIC Educational Resources Information Center

Dessy, Raymond E.

1982-01-01

Local area networks are common communication conduits allowing various terminals, computers, discs, printers, and other electronic devices to intercommunicate over short distances. Discusses the vocabulary of such networks including RS-232C point-to-point and IEEE-488 multidrop protocols; error detection; message packets; multiplexing; star, ring,…

Dependency Links Can Hinder the Evolution of Cooperation in the Prisoner’s Dilemma Game on Lattices and Networks

PubMed Central

Wang, Xuwen; Nie, Sen; Wang, Binghong

2015-01-01

Networks with dependency links are more vulnerable when facing the attacks. Recent research also has demonstrated that the interdependent groups support the spreading of cooperation. We study the prisoner’s dilemma games on spatial networks with dependency links, in which a fraction of individual pairs is selected to depend on each other. The dependency individuals can gain an extra payoff whose value is between the payoff of mutual cooperation and the value of temptation to defect. Thus, this mechanism reflects that the dependency relation is stronger than the relation of ordinary mutual cooperation, but it is not large enough to cause the defection of the dependency pair. We show that the dependence of individuals hinders, promotes and never affects the cooperation on regular ring networks, square lattice, random and scale-free networks, respectively. The results for the square lattice and regular ring networks are demonstrated by the pair approximation. PMID:25798579

Circuit variability interacts with excitatory-inhibitory diversity of interneurons to regulate network encoding capacity.

PubMed

Tsai, Kuo-Ting; Hu, Chin-Kun; Li, Kuan-Wei; Hwang, Wen-Liang; Chou, Ya-Hui

2018-05-23

Local interneurons (LNs) in the Drosophila olfactory system exhibit neuronal diversity and variability, yet it is still unknown how these features impact information encoding capacity and reliability in a complex LN network. We employed two strategies to construct a diverse excitatory-inhibitory neural network beginning with a ring network structure and then introduced distinct types of inhibitory interneurons and circuit variability to the simulated network. The continuity of activity within the node ensemble (oscillation pattern) was used as a readout to describe the temporal dynamics of network activity. We found that inhibitory interneurons enhance the encoding capacity by protecting the network from extremely short activation periods when the network wiring complexity is very high. In addition, distinct types of interneurons have differential effects on encoding capacity and reliability. Circuit variability may enhance the encoding reliability, with or without compromising encoding capacity. Therefore, we have described how circuit variability of interneurons may interact with excitatory-inhibitory diversity to enhance the encoding capacity and distinguishability of neural networks. In this work, we evaluate the effects of different types and degrees of connection diversity on a ring model, which may simulate interneuron networks in the Drosophila olfactory system or other biological systems.

Seal Technology for Liquid Oxygen (LOX) Turbopumps

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur; Hamm, Robert

1985-01-01

Two types of advanced seals for liquid oxygen (LOX) turbopumps were investigated. One was a spiral-groove face seal whose function is to seal high-pressure LOX at the impeller end of the turbopump. The other was a floating-ring, Rayleigh-step, helium buffered seal used to prevent LOX ingress to the turbine side of the unit. For each seal type, two sizes were investigated (50 and 20 mm). A turbine-driven test rig was designed and manufactured, and a test program was completed on the 50 mm floating-ring, Rayleigh-step, helium buffered seal. Significant results were: vaporization in the flow path could cause failure by overheating; therefore, the spiral-groove pumping portion of the seal that provides the fluid film must circulate fluid without disruption if vaporization occurs in the sealing dam. This is successfully accomplished by a pressure-balanced spiral-groove concept that is described. The spiral-groove configuration is affected by turbulence in the fluid film and pressure drops due to fluid inertia at sudden contractions. The net results of these effects are deep grooves, large operating films, and high power loss when compared against seals operating with laminar films. Turbulence and inertia are induced by the high-density and low-viscosity characteristics of LOX. The program clearly pointed out the need to consider system environmental factors such as thermal and centrifugal distortions and rotor vibrations in the seal design.

Succinimide Formation from an NGR-Containing Cyclic Peptide: Computational Evidence for Catalytic Roles of Phosphate Buffer and the Arginine Side Chain.

PubMed

Kirikoshi, Ryota; Manabe, Noriyoshi; Takahashi, Ohgi

2017-02-16

The Asn-Gly-Arg (NGR) motif and its deamidation product iso Asp-Gly-Arg ( iso DGR) have recently attracted considerable attention as tumor-targeting ligands. Because an NGR-containing peptide and the corresponding iso DGR-containing peptide target different receptors, the spontaneous NGR deamidation can be used in dual targeting strategies. It is well known that the Asn deamidation proceeds via a succinimide derivative. In the present study, we computationally investigated the mechanism of succinimide formation from a cyclic peptide, c[CH₂CO-NGRC]-NH₂, which has recently been shown to undergo rapid deamidation in a phosphate buffer. An H₂PO₄ - ion was explicitly included in the calculations. We employed the density functional theory using the B3LYP functional. While geometry optimizations were performed in the gas phase, hydration Gibbs energies were calculated by the SM8 (solvation model 8) continuum model. We have found a pathway leading to the five-membered ring tetrahedral intermediate in which both the H₂PO₄ - ion and the Arg side chain act as catalyst. This intermediate, once protonated at the NH₂ group on the five-membered ring, was shown to easily undergo NH₃ elimination leading to the succinimide formation. This study is the first to propose a possible catalytic role for the Arg side chain in the NGR deamidation.

Mitigating TCP Degradation over Intermittent Link Failures using Intermediate Buffers

DTIC Science & Technology

2006-06-01

signal strength [10]. The Preemptive routing in ad hoc networks [10] attempts to predict that a route will fail by looking at the signal power of the...when the error rate is high there are non -optimal back offs in the Retransmission Timeout. And third, in the high error situation the slow start...network storage follows. In Beck et. al. [3], Logistical Networking is outlined as a means of storing data throughout the network. End to end

The North American Drought Atlas: Tree-Ring Reconstructions of Drought Variability for Climate Modeling and Assessment

NASA Astrophysics Data System (ADS)

Cook, E. R.

2007-05-01

The North American Drought Atlas describes a detailed reconstruction of drought variability from tree rings over most of North America for the past 500-1000 years. The first version of it, produced over three years ago, was based on a network of 835 tree-ring chronologies and a 286-point grid of instrumental Palmer Drought Severity Indices (PDSI). These gridded PDSI reconstructions have been used in numerous published studies now that range from modeling fire in the American West, to the impact of drought on palaeo-Indian societies, and to the determination of the primary causes of drought over North America through climate modeling experiments. Some examples of these applications will be described to illustrate the scientific value of these large-scale reconstructions of drought. Since the development and free public release of Version 1 of the North American Drought Atlas (see http:iridl.ldeo.columbia.edu/SOURCES/.LDEO/.TRL/.NADA2004/.pdsi-atlas.html), great improvements have been made in the critical tree-ring network used to reconstruct PDSI at each grid point. This network has now been enlarged to 1743 annual tree-ring chronologies, which greatly improves the density of tree-ring records in certain parts of the grid, especially in Canada and Mexico. In addition, the number of tree-ring records that extend back before AD 1400 has been substantially increased. These developments justify the creation of Version 2 of the North American Drought Atlas. In this talk I will describe this new version of the drought atlas and some of its properties that make it a significant improvement over the previous version. The new product provides enhanced resolution of the spatial and temporal variability of prolonged drought such as the late 16th century event that impacted regions of both Mexico and the United States. I will also argue for the North American Drought Atlas being used as a template for the development of large-scale drought reconstructions in other land areas of the Northern Hemisphere where sufficient tree-ring data exist. By doing so, the importance of this product to the modeling community will be significantly enhanced.

Real time characterization of hydrodynamics in optically trapped networks of micro-particles.

PubMed

Curran, Arran; Yao, Alison M; Gibson, Graham M; Bowman, Richard; Cooper, Jon M; Padgett, Miles L

2010-04-01

The hydrodynamic interactions of micro-silica spheres trapped in a variety of networks using holographic optical tweezers are measured and characterized in terms of their predicted eigenmodes. The characteristic eigenmodes of the networks are distinguishable within 20-40 seconds of acquisition time. Three different multi-particle networks are considered; an eight-particle linear chain, a nine-particle square grid and, finally, an eight-particle ring. The eigenmodes and their decay rates are shown to behave as predicted by the Oseen tensor and the Langevin equation, respectively. Finally, we demonstrate the potential of using our micro-ring as a non-invasive sensor to the local environmental viscosity, by showing the distortion of the eigenmode spectrum due to the proximity of a planar boundary. ((c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Molecular organization of cytokinesis nodes and contractile rings by super-resolution fluorescence microscopy of live fission yeast

PubMed Central

Laplante, Caroline; Huang, Fang; Tebbs, Irene R.; Bewersdorf, Joerg; Pollard, Thomas D.

2016-01-01

Cytokinesis in animals, fungi, and amoebas depends on the constriction of a contractile ring built from a common set of conserved proteins. Many fundamental questions remain about how these proteins organize to generate the necessary tension for cytokinesis. Using quantitative high-speed fluorescence photoactivation localization microscopy (FPALM), we probed this question in live fission yeast cells at unprecedented resolution. We show that nodes, protein assembly precursors to the contractile ring, are discrete structural units with stoichiometric ratios and distinct distributions of constituent proteins. Anillin Mid1p, Fes/CIP4 homology-Bin/amphiphysin/Rvs (F-BAR) Cdc15p, IQ motif containing GTPase-activating protein (IQGAP) Rng2p, and formin Cdc12p form the base of the node that anchors the ends of myosin II tails to the plasma membrane, with myosin II heads extending into the cytoplasm. This general node organization persists in the contractile ring where nodes move bidirectionally during constriction. We observed the dynamics of the actin network during cytokinesis, starting with the extension of short actin strands from nodes, which sometimes connected neighboring nodes. Later in cytokinesis, a broad network of thick bundles coalesced into a tight ring around the equator of the cell. The actin ring was ∼125 nm wide and ∼125 nm thick. These observations establish the organization of the proteins in the functional units of a cytokinetic contractile ring. PMID:27647921

A Formal Approach to the Provably Correct Synthesis of Mission Critical Embedded Software for Multi Core Embedded Platforms

DTIC Science & Technology

2014-04-01

synchronization primitives based on preset templates can result in over synchronization if unchecked, possibly creating deadlock situations. Further...inputs rather than enforcing synchronization with a global clock. MRICDF models software as a network of communicating actors. Four primitive actors...control wants to send interrupt or not. Since this is shared buffer, a semaphore mechanism is assumed to synchronize the read/write of this buffer. The

ARPANET Routing Algorithm Improvements. Volume 1

DTIC Science & Technology

1980-08-01

the currently active PROCESS (at the head of the scheduling list). TIME returns the time. PASSIVATE puts the CURRENT PROCESS to sleep , and wakes uD...Ccntract. Network buffer managemenL issues are discussed and a new buffer managemet scheme for f the ARPANET is designed. Logical addressing is discussed...and a design is given for a logical addressing scheme suitable for ARPANET or DIN II. The applicability of ARPANET Routing to DIN II is evaluaced. The

[Research advances in dendrochronology].

PubMed

Fang, Ke-Yan; Chen, Qiu-Yan; Liu, Chang-Zhi; Cao, Chun-Fu; Chen, Ya-Jun; Zhou, Fei-Fei

2014-07-01

Tree-ring studies in China have achieved great advances since the 1990s, particularly for the dendroclimatological studies which have made some influence around the world. However, because of the uneven development, limited attention has been currently paid on the other branches of dendrochronology. We herein briefly compared the advances of dendrochronology in China and of the world and presented suggestions on future dendrochronological studies. Large-scale tree-ring based climate reconstructions in China are highly needed by employing mathematical methods and a high quality tree-ring network of the ring-width, density, stable isotope and wood anatomy. Tree-ring based field climate reconstructions provide potentials on explorations of climate forcings during the reconstructed periods via climate diagnosis and process simulation.

High-Speed Optical Wide-Area Data-Communication Network

NASA Technical Reports Server (NTRS)

Monacos, Steve P.

1994-01-01

Proposed fiber-optic wide-area network (WAN) for digital communication balances input and output flows of data with its internal capacity by routing traffic via dynamically interconnected routing planes. Data transmitted optically through network by wavelength-division multiplexing in synchronous or asynchronous packets. WAN implemented with currently available technology. Network is multiple-ring cyclic shuffle exchange network ensuring traffic reaches its destination with minimum number of hops.

Quality of Service for Real-Time Applications Over Next Generation Data Networks

NASA Technical Reports Server (NTRS)

Atiquzzaman, Mohammed; Jain, Raj

2001-01-01

This project, which started on January 1, 2000, was funded by the NASA Glenn Research Center for duration of one year. The deliverables of the project included the following tasks: (1) Study of QoS mapping between the edge and core networks envisioned in the Next Generation networks will provide us with the QoS guarantees that can be obtained from next generation networks; (2) Buffer management techniques to provide strict guarantees to real-time end-to-end applications through preferential treatment to packets belonging to real-time applications. In particular, use of ECN to help reduce the loss on high bandwidth-delay product satellite networks needs to be studied; (3) Effect of Prioritized Packet Discard to increase goodput of the network and reduce the buffering requirements in the ATM switches; (4) Provision of new IP circuit emulation services over Satellite IP backbones using MPLS will be studied; and (5) Determine the architecture and requirements for internetworking ATN and the Next Generation Internet for real-time applications. The project has been completed on time. All the objectives and deliverables of the project have been completed. Research results obtained from this project have been published in a number of papers in journals, conferences, and technical reports, included in this document.

Robust gap repair in the contractile ring ensures timely completion of cytokinesis

PubMed Central

Maiato, Helder; Pinto, Inês Mendes; Rubinstein, Boris

2016-01-01

Cytokinesis in animal cells requires the constriction of an actomyosin contractile ring, whose architecture and mechanism remain poorly understood. We use laser microsurgery to explore the biophysical properties of constricting rings in Caenorhabditis elegans embryos. Laser cutting causes rings to snap open. However, instead of disintegrating, ring topology recovers and constriction proceeds. In response to severing, a finite gap forms and is repaired by recruitment of new material in an actin polymerization–dependent manner. An open ring is able to constrict, and rings repair from successive cuts. After gap repair, an increase in constriction velocity allows cytokinesis to complete at the same time as controls. Our analysis demonstrates that tension in the ring increases while net cortical tension at the site of ingression decreases throughout constriction and suggests that cytokinesis is accomplished by contractile modules that assemble and contract autonomously, enabling local repair of the actomyosin network. Consequently, cytokinesis is a highly robust process impervious to discontinuities in contractile ring structure. PMID:27974482

Semiconductor ring lasers coupled by a single waveguide

NASA Astrophysics Data System (ADS)

Coomans, W.; Gelens, L.; Van der Sande, G.; Mezosi, G.; Sorel, M.; Danckaert, J.; Verschaffelt, G.

2012-06-01

We experimentally and theoretically study the characteristics of semiconductor ring lasers bidirectionally coupled by a single bus waveguide. This configuration has, e.g., been suggested for use as an optical memory and as an optical neural network motif. The main results are that the coupling can destabilize the state in which both rings lase in the same direction, and it brings to life a state with equal powers at both outputs. These are both undesirable for optical memory operation. Although the coupling between the rings is bidirectional, the destabilization occurs due to behavior similar to an optically injected laser system.

The TurboLAN project. Phase 1: Protocol choices for high speed local area networks. Phase 2: TurboLAN Intelligent Network Adapter Card, (TINAC) architecture

NASA Technical Reports Server (NTRS)

Alkhatib, Hasan S.

1991-01-01

The hardware and the software architecture of the TurboLAN Intelligent Network Adapter Card (TINAC) are described. A high level as well as detailed treatment of the workings of various components of the TINAC are presented. The TINAC is divided into the following four major functional units: (1) the network access unit (NAU); (2) the buffer management unit; (3) the host interface unit; and (4) the node processor unit.

GAPR2: A DTN Routing Protocol for Communications in Challenged, Degraded, and Denied Environments

DTIC Science & Technology

2015-09-01

Transmission Speed Vs. Latency Figure 4.7: Helsinki Simulation Set 2, High Network Load and Small Buffers Analysis of Delivery Ratio in Helsinki Simulation...ipnsig.org/. [17] MANET routing, class notes for CS4554: Network modeling and analysis . 119 [18] S. Basagni et al. Mobile ad hoc networking . John...Wiley & Sons, 2004. [19] E. Royer et al. A review of current routing protocols for ad hoc mobile wireless networks . Personal Communications, IEEE, 6(2

Influence of Packing on Low Energy Vibrations of Densified Glasses

NASA Astrophysics Data System (ADS)

Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo

2013-12-01

A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.

Study on the method of improving the flashover voltage of 110kV suspension porcelain insulators based on neural network genetic algorithm

NASA Astrophysics Data System (ADS)

Zhang, Ruiqi; Cai, Li; Chen, Junwu; Wang, Luo; Tan, Xuefeng

2018-04-01

This paper presents a new method to improve 110kV porcelain insulator flashover voltage by adding a metal ring on the insulator cap, which can not only effectively reduce the field strength of the steel cap, but also reduce the tangential field intensity of the umbrella group and inhibit the development of the discharge process, thus the flashover voltage can be increased. The surface strength calculation model of 110kV porcelain insulator is established by the finite element method (FEM), and the parameters of the metal ring are designed by neural network genetic algorithm (BP-GA). Then the experiments were carried out to verify the results, and the results show that the metal ring plate under the optimum parameters can greatly improve the flashover voltage.

Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructions

NASA Astrophysics Data System (ADS)

Anchukaitis, Kevin J.; Wilson, Rob; Briffa, Keith R.; Büntgen, Ulf; Cook, Edward R.; D'Arrigo, Rosanne; Davi, Nicole; Esper, Jan; Frank, David; Gunnarson, Björn E.; Hegerl, Gabi; Helama, Samuli; Klesse, Stefan; Krusic, Paul J.; Linderholm, Hans W.; Myglan, Vladimir; Osborn, Timothy J.; Zhang, Peng; Rydval, Milos; Schneider, Lea; Schurer, Andrew; Wiles, Greg; Zorita, Eduardo

2017-05-01

Climate field reconstructions from networks of tree-ring proxy data can be used to characterize regional-scale climate changes, reveal spatial anomaly patterns associated with atmospheric circulation changes, radiative forcing, and large-scale modes of ocean-atmosphere variability, and provide spatiotemporal targets for climate model comparison and evaluation. Here we use a multiproxy network of tree-ring chronologies to reconstruct spatially resolved warm season (May-August) mean temperatures across the extratropical Northern Hemisphere (40-90°N) using Point-by-Point Regression (PPR). The resulting annual maps of temperature anomalies (750-1988 CE) reveal a consistent imprint of volcanism, with 96% of reconstructed grid points experiencing colder conditions following eruptions. Solar influences are detected at the bicentennial (de Vries) frequency, although at other time scales the influence of insolation variability is weak. Approximately 90% of reconstructed grid points show warmer temperatures during the Medieval Climate Anomaly when compared to the Little Ice Age, although the magnitude varies spatially across the hemisphere. Estimates of field reconstruction skill through time and over space can guide future temporal extension and spatial expansion of the proxy network.

Perceived ethnic discrimination and depressive symptoms: the buffering effects of ethnic identity, religion and ethnic social network.

PubMed

Ikram, Umar Z; Snijder, Marieke B; de Wit, Matty A S; Schene, Aart H; Stronks, Karien; Kunst, Anton E

2016-05-01

Perceived ethnic discrimination (PED) is positively associated with depressive symptoms in ethnic minority groups in Western countries. Psychosocial factors may buffer against the health impact of PED, but evidence is lacking from Europe. We assessed whether ethnic identity, religion, and ethnic social network act as buffers in different ethnic minority groups in Amsterdam, the Netherlands. Baseline data were used from the HEalthy Living In a Urban Setting study collected from January 2011 to June 2014. The random sample included 2501 South-Asian Surinamese, 2292 African Surinamese, 1877 Ghanaians, 2626 Turks, and 2484 Moroccans aged 18-70 years. Depressive symptoms were assessed using the Patient Health Questionnaire-9. PED was measured with the Everyday Discrimination Scale. Ethnic identity was assessed using the Psychological Acculturation Scale. Practicing religion was determined. Ethnic social network was assessed with the number of same-ethnic friends and amount of leisure time spent with same-ethnic people. PED was positively associated with depressive symptoms in all groups. The association was weaker among (a) those with strong ethnic identity in African Surinamese and Ghanaians, (b) those practicing religion among African Surinamese and Moroccans, (c) those with many same-ethnic friends in South-Asian Surinamese, Ghanaians, and Turks, and (d) those who spend leisure time with same-ethnic people among African Surinamese and Turks. Ethnic identity, religion, and ethnic social network weakened the association between PED and depressive symptoms, but the effects differed by ethnic minority group. These findings suggest that ethnic minority groups employ different resources to cope with PED.

Forward modeling of tree-ring data: a case study with a global network

NASA Astrophysics Data System (ADS)

Breitenmoser, P. D.; Frank, D.; Brönnimann, S.

2012-04-01

Information derived from tree-rings is one of the most powerful tools presently available for studying past climatic variability as well as identifying fundamental relationships between tree-growth and climate. Climate reconstructions are typically performed by extending linear relationships, established during the overlapping period of instrumental and climate proxy archives into the past. Such analyses, however, are limited by methodological assumptions, including stationarity and linearity of the climate-proxy relationship. We investigate climate and tree-ring data using the Vaganov-Shashkin-Lite (VS-Lite) forward model of tree-ring width formation to examine the relations among actual tree growth and climate (as inferred from the simulated chronologies) to reconstruct past climate variability. The VS-lite model has been shown to produce skill comparable to that achieved using classical dendrochronological statistical modeling techniques when applied on simulations of a network of North American tree-ring chronologies. Although the detailed mechanistic processes such as photosynthesis, storage, or cell processes are not modeled directly, the net effect of the dominating nonlinear climatic controls on tree-growth are implemented into the model by the principle of limiting factors and threshold growth response functions. The VS-lite model requires as inputs only latitude, monthly mean temperature and monthly accumulated precipitation. Hence, this simple, process-based model enables ring-width simulation at any location where monthly climate records exist. In this study, we analyse the growth response of simulated tree-rings to monthly climate conditions obtained from the 20th century reanalysis project back to 1871. These simulated tree-ring chronologies are compared to the climate-driven variability in worldwide observed tree-ring chronologies from the International Tree Ring Database. Results point toward the suitability of the relationship among actual tree growth and climate (as inferred from the simulated chronologies) for use in global palaeoclimate reconstructions.

The impact of electric vehicles on the outlook of future energy system

NASA Astrophysics Data System (ADS)

Zhuk, A.; Buzoverov, E.

2018-02-01

Active promotion of electric vehicles (EVs) and technology of fast EV charging in the medium term may cause significant peak loads on the energy system, what necessitates making strategic decisions related to the development of generating capacities, distribution networks with EV charging infrastructure, and priorities in the development of battery electric vehicles and vehicles with electrochemical generators. The paper analyses one of the most significant aspects of joint development of electric transport system and energy system in the conditions of substantial growth of energy consumption by EVs. The assessments of per-unit-costs of operation and depreciation of EV power unit were made, taking into consideration the expenses of electric power supply. The calculations show that the choice of electricity buffering method for EV fast charging depends on the character of electricity infrastructure in the region where the electric transport is operating. In the conditions of high density of electricity network and a large number of EVs, the stationary storage facilities or the technology of distributed energy storage in EV batteries - vehicle-to-grid (V2G) technology may be used for buffering. In the conditions of low density and low capacity of electricity networks, the most economical solution could be usage of EVs with traction power units based on the combination of air-aluminum electrochemical generator and a buffer battery of small capacity.

Moving the boundary between wavelength resources in optical packet and circuit integrated ring network.

PubMed

Furukawa, Hideaki; Miyazawa, Takaya; Wada, Naoya; Harai, Hiroaki

2014-01-13

Optical packet and circuit integrated (OPCI) networks provide both optical packet switching (OPS) and optical circuit switching (OCS) links on the same physical infrastructure using a wavelength multiplexing technique in order to deal with best-effort services and quality-guaranteed services. To immediately respond to changes in user demand for OPS and OCS links, OPCI networks should dynamically adjust the amount of wavelength resources for each link. We propose a resource-adjustable hybrid optical packet/circuit switch and transponder. We also verify that distributed control of resource adjustments can be applied to the OPCI ring network testbed we developed. In cooperation with the resource adjustment mechanism and the hybrid switch and transponder, we demonstrate that automatically allocating a shared resource and moving the wavelength resource boundary between OPS and OCS links can be successfully executed, depending on the number of optical paths in use.

Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics

PubMed Central

Bennett, Eric J.; Rush, John; Gygi, Steven P.; Harper, J. Wade

2010-01-01

Dynamic reorganization of signaling systems frequently accompany pathway perturbations, yet quantitative studies of network remodeling by pathway stimuli are lacking. Here, we report the development of a quantitative proteomics platform centered on multiplex Absolute Quantification (AQUA) technology to elucidate the architecture of the cullin-RING ubiquitin ligase (CRL) network and to evaluate current models of dynamic CRL remodeling. Current models suggest that CRL complexes are controlled by cycles of CRL deneddylation and CAND1 binding. Contrary to expectations, acute CRL inhibition with MLN4924, an inhibitor of the NEDD8-activating enzyme, does not result in a global reorganization of the CRL network. Examination of CRL complex stoichiometry reveals that, independent of cullin neddylation, a large fraction of cullins are assembled with adaptor modules while only a small fraction are associated with CAND1. These studies suggest an alternative model of CRL dynamicity where the abundance of adaptor modules, rather than cycles of neddylation and CAND1 binding, drives CRL network organization. PMID:21145461

Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics.

PubMed

Bennett, Eric J; Rush, John; Gygi, Steven P; Harper, J Wade

2010-12-10

Dynamic reorganization of signaling systems frequently accompanies pathway perturbations, yet quantitative studies of network remodeling by pathway stimuli are lacking. Here, we report the development of a quantitative proteomics platform centered on multiplex absolute quantification (AQUA) technology to elucidate the architecture of the cullin-RING ubiquitin ligase (CRL) network and to evaluate current models of dynamic CRL remodeling. Current models suggest that CRL complexes are controlled by cycles of CRL deneddylation and CAND1 binding. Contrary to expectations, acute CRL inhibition with MLN4924, an inhibitor of the NEDD8-activating enzyme, does not result in a global reorganization of the CRL network. Examination of CRL complex stoichiometry reveals that, independent of cullin neddylation, a large fraction of cullins are assembled with adaptor modules, whereas only a small fraction are associated with CAND1. These studies suggest an alternative model of CRL dynamicity where the abundance of adaptor modules, rather than cycles of neddylation and CAND1 binding, drives CRL network organization. Copyright © 2010 Elsevier Inc. All rights reserved.

Progress towards the use of publicly available data networks to conduct cross-scale historical reconstructions of carbon dynamics in US Drylands

NASA Astrophysics Data System (ADS)

Washington-Allen, R. A.; Landolt, K.; Emanuel, R. E.; Therrell, M. D.; Nagle, N.; Grissino-Mayer, H. D.; Poulter, B.

2016-12-01

Emergent scale properties of water-limited or Dryland ecosystem's carbon flux are unknown at spatial scales from local to global and time scales of 10 - 1000 years or greater. The width of a tree ring is a metric of production that has been correlated with the amount of precipitation. This relationship has been used to reconstruct rainfall and fire histories in the Drylands of the southwestern US. The normalized difference vegetation index (NDVI) is globally measured by selected satellite sensors and is highly correlated with the fraction of solar radiation which is absorbed for photosynthesis by plants (FPAR), as well as with vegetation biomass, net primary productivity (NPP), and tree ring width. Publicly available web-based archives of free NDVI and tree ring data exist and have allowed historical temporal reconstructions of carbon dynamics for the past 300 to 500 years. Climate and tree ring databases have been used to spatially reconstruct drought dynamics for the last 500 years in the western US. In 2007, we hypothesized that NDVI and tree ring width could be used to spatially reconstruct carbon dynamics in US Drylands. In 2015, we succeeded with a 300-year historical spatial reconstruction of NPP in California using a Blue Oak tree ring chronology. Online eddy covariance flux tower measures of NPP are well correlated with satellite measures of NPP. This suggests that net ecosystem exchange (NEE = NPP - soil Respiration) could be historically reconstructed across Drylands. Ongoing research includes 1) scaling historical spatial reconstruction to US Drylands, 2) comparing the use of single versus multiple tree ring species (r2 = 68) and 3) use of the eddy flux tower network, remote sensing, and tree ring data to historically spatially reconstruct Dryland NEE.

Study of Adversarial and Defensive Components in an Experimental Machinery Control Systems Laboratory Environment

DTIC Science & Technology

2014-09-01

prevention system (IPS), capable of performing real-time traffic analysis and packet logging on IP networks [25]. Snort’s features include protocol... analysis and content searching/matching. Snort can detect a variety of attacks and network probes, such as buffer overflows, port scans and OS...www.digitalbond.com/tools/the- rack/jtr-s7-password-cracking/ Kismet Mike Kershaw Cross- platform Open source wireless network detector and wireless sniffer

All-optical LAN architectures based on arrayed waveguide grating multiplexers

NASA Astrophysics Data System (ADS)

Woesner, Hagen

1998-10-01

The paper presents optical LAN topologies which are made possible using an Arrayed Waveguide Grating Multiplexer (AWGM) instead of a passive star coupler to interconnect stations in an all-optical LAN. Due to the collision-free nature of an AWGM it offers the n-fold bandwidth compared to the star coupler. Virtual ring topologies appear (one ring on each wavelength) if the number of stations attached to the AWGM is a prime number. A method to construct larger networks using Cayley graphs is shown. An access protocol to avoid collisions on the proposed network is outlined.

Demonstration of an SOA-assisted open metro-access infrastructure for heterogeneous services.

PubMed

Schmuck, H; Bonk, R; Poehlmann, W; Haslach, C; Kuebart, W; Karnick, D; Meyer, J; Fritzsche, D; Weis, E; Becker, J; Freude, W; Pfeiffer, T

2014-01-13

An open converged metro-access network approach allows for sharing optical layer resources like fibers and optical spectrum among different services and operators. We demonstrated experimentally the feasibility of such a concept by the simultaneous operation of multiple services showing different modulation formats and multiplexing techniques. Flexible access nodes are implemented including semiconductor optical amplifiers to create a transparent and reconfigurable optical ring network. The impact of cascaded optical amplifiers on the signal quality is studied along the ring. In addition, the influence of high power rival signals in the same waveband and in the same fiber is analyzed.

Effect of placental tissue on inhibition of uterine contraction by nitric oxide donors.

PubMed

Syal, A; Okawa, T; Vedernikov, Y; Chwalisz, K; Saade, G R; Garfield, R E

1999-08-01

Our purpose was to test the hypothesis that placental tissue modulates the effect of nitric oxide on spontaneous uterine contractility in pregnant rats. Rings (approximately 4 mm) of uterus taken from rats on day 14 (midpregnancy, n = 6), day 18 (late pregnancy, n = 4), and day 22 (term, n = 4) of gestation were placed in organ chambers filled with Krebs-bicarbonate buffer bubbled with 5% carbon dioxide in air (37 degrees C, pH approximately 7.4) for isometric tension recording. In some rings a piece of placenta was left attached to the uterine wall. In the other rings the fetuses, placentas, and membranes were removed completely. Change of spontaneous contractions of the rings (percentage change of basal integral activity for 10 minutes) in response to cumulative concentrations of the nitric oxide donors diethylamine-nitric oxide and nitroglycerin (10(-6) mol/L to 10(-4) mol/L) were compared between rings with and without placenta. Diethylamine-nitric oxide and nitroglycerin inhibited spontaneous uterine contractions in rings from midpregnancy, in both the absence and the presence of placenta. In rings from midpregnancy, the maximal inhibition of contractions by diethylamine-nitric oxide but not by nitroglycerin was significantly (P <.05) higher in the presence (26.7% +/- 3.5% of basal activity) than in the absence (39. 6% +/- 3.3%) of placenta. Inhibition of contraction by nitric oxide donors in rings from late and term pregnancy was less than in midpregnancy, and the presence of placental tissue did not influence the responses. The presence of placental tissue enhances inhibition of uterine contractility by agents that spontaneously release nitric oxide, such as diethylamine-nitric oxide, but not by nitroglycerin, which requires metabolic transformation for nitric oxide to be released. Refractoriness to nitric oxide near or at term does not depend on the presence or absence of placental tissue.

Buffered Qualitative Stability explains the robustness and evolvability of transcriptional networks

PubMed Central

Albergante, Luca; Blow, J Julian; Newman, Timothy J

2014-01-01

The gene regulatory network (GRN) is the central decision‐making module of the cell. We have developed a theory called Buffered Qualitative Stability (BQS) based on the hypothesis that GRNs are organised so that they remain robust in the face of unpredictable environmental and evolutionary changes. BQS makes strong and diverse predictions about the network features that allow stable responses under arbitrary perturbations, including the random addition of new connections. We show that the GRNs of E. coli, M. tuberculosis, P. aeruginosa, yeast, mouse, and human all verify the predictions of BQS. BQS explains many of the small- and large‐scale properties of GRNs, provides conditions for evolvable robustness, and highlights general features of transcriptional response. BQS is severely compromised in a human cancer cell line, suggesting that loss of BQS might underlie the phenotypic plasticity of cancer cells, and highlighting a possible sequence of GRN alterations concomitant with cancer initiation. DOI: http://dx.doi.org/10.7554/eLife.02863.001 PMID:25182846

End-to-end QoS bounds for RTP-based service subnetworks

NASA Astrophysics Data System (ADS)

Pitts, Jonathan M.; Schormans, John A.

1999-11-01

With the increasing focus on traffic prioritization to support voice-data integration in corporate intranets, practical methods are needed to dimension and manage cost efficient service partitions. This is particularly important for the provisioning of real time, delay sensitive services such as telephony and voice/video conferencing applications. Typically these can be provided over RTP/UDP/IP or ATM DBR/SBR bearers but, irrespective of the specific networking technology, the switches or routers need to implement some form of virtual buffer management with queue scheduling mechanisms to provide partitioning. The key requirement is for operators of such networks to be able to dimension the partitions and virtual buffer sizes for efficient resource utilization, instead of simply over-dimensioning. This paper draws on recent work at Queen Mary, University of London, supported by the UK Engineering and Physical Sciences Research Council, to investigate approximate analytical methods for assessing end to end delay variation bounds in cell based and packet based networks.

Buffered Qualitative Stability explains the robustness and evolvability of transcriptional networks.

PubMed

Albergante, Luca; Blow, J Julian; Newman, Timothy J

2014-09-02

The gene regulatory network (GRN) is the central decision-making module of the cell. We have developed a theory called Buffered Qualitative Stability (BQS) based on the hypothesis that GRNs are organised so that they remain robust in the face of unpredictable environmental and evolutionary changes. BQS makes strong and diverse predictions about the network features that allow stable responses under arbitrary perturbations, including the random addition of new connections. We show that the GRNs of E. coli, M. tuberculosis, P. aeruginosa, yeast, mouse, and human all verify the predictions of BQS. BQS explains many of the small- and large-scale properties of GRNs, provides conditions for evolvable robustness, and highlights general features of transcriptional response. BQS is severely compromised in a human cancer cell line, suggesting that loss of BQS might underlie the phenotypic plasticity of cancer cells, and highlighting a possible sequence of GRN alterations concomitant with cancer initiation. Copyright © 2014, Albergante et al.

Experimental GMPLS-Based Provisioning for Future All-Optical DPRing-Based MAN

NASA Astrophysics Data System (ADS)

Mu�oz, Ra�l; V�ctor Mart�nez Rivera, Ricardo; Sorribes, Jordi; Junyent Giralt, Gabriel

2005-10-01

Given the abundance and strategic importance of ring fiber plants in metropolitan area networks (MANs), and the accelerating growth of Internet traffic, it is crucial to extend the existing Internet protocol (IP)-based generalized multiprotocol label switching (GMPLS) framework to provision dynamic wavelength division multiplexing (WDM) optical rings. Nevertheless, the emerging GMPLS-based lightpath provisioning does not cover the intricacies of optical rings. No GMPLS standard exists for optical add-drop multiplexer (OADM) rings, relying instead upon proprietary static solution. The objective of this paper is to propose and evaluate novel GMPLS-based lightpath signaling and wavelength reservation schemes specifically designed for dedicated protection ring (DPRing)-based MANs. Performance evaluation has been carried out in a GMPLS-based testbed named ADRENALINE.

Hsp90 interaction with Cdc2 and Plo1 kinases contributes to actomyosin ring condensation in fission yeast.

PubMed

Santino, Andrea; Tallada, Victor A; Jimenez, Juan; Garzón, Andrés

2012-08-01

In Schizosaccharomyces pombe, cytokinesis occurs by ordered recruitment of actomyosin components at the division site, followed by lateral condensation to produce a ring-like structure early in anaphase, which eventually matures and contracts at the end of mitosis. We found that in temperature-sensitive hsp90-w1 mutant cells, encoding an Hsp90 mutant protein, ring components were recruited to form a cortical network at the division site, but this network failed to condense into a compact ring, suggesting a role for Hsp90 in this particular step. hsp90-w1 mutant shows strong genetic interaction with specific mutant alleles of the fission yeast cdc2, such as cdc2-33. Interestingly, actomyosin ring defects in hsp90-w1 cdc2-33 mutant cells resembled that of hsp90-w1 single mutant at restrictive temperature. Noteworthy, similar genetic interaction was found with a mutant allele of polo-like kinase, plo1-ts4, suggesting that Hsp90 collaborates with Cdc2 and Plo1 cell cycle kinases to condense medial ring components. In vitro analyses suggested that Cdc2 and Plo1 physically interact with Hsp90. Association of Cdc2 to Hsp90 was ATP independent, while Plo1 binds to this chaperone in an ATP-dependent manner, indicating that these two kinases interact with different Hsp90 complexes. Overall, our analyses of hsp90-w1 reveal a possible role for this chaperone in medial ring condensation in association with Cdc2 and Plo1 kinases.

Red blood cell (RBC) suspensions in confined microflows: Pressure-flow relationship.

PubMed

Stauber, Hagit; Waisman, Dan; Korin, Netanel; Sznitman, Josué

2017-10-01

Microfluidic-based assays have become increasingly popular to explore microcirculation in vitro. In these experiments, blood is resuspended to a desired haematocrit level in a buffer solution, where frequent choices for preparing RBC suspensions comprise notably Dextran and physiological buffer. Yet, the rational for selecting one buffer versus another is often ill-defined and lacks detailed quantification, including ensuing changes in RBC flow characteristics. Here, we revisit RBC suspensions in microflows and attempt to quantify systematically some of the differences emanating between buffers. We measure bulk flow rate (Q) of RBC suspensions, using PBS- and Dextran-40, as a function of the applied pressure drop (ΔP) for two hematocrits (∼0% and 23%). Two distinct microfluidic designs of varying dimensions are employed: a straight channel larger than and a network array similar to the size of individual RBCs. Using the resulting pressure-flow curves, we extract the equivalent hydrodynamic resistances and estimate the relative viscosities. These efforts are a first step in rigorously quantifying the influence of the 'background' buffer on RBC flows within microfluidic devices and thereby underline the importance of purposefully selecting buffer suspensions for microfluidic in vitro assays. Copyright © 2017. Published by Elsevier Ltd.

Network Hubs Buffer Environmental Variation in Saccharomyces cerevisiae

PubMed Central

Levy, Sasha F; Siegal, Mark L

2008-01-01

Regulatory and developmental systems produce phenotypes that are robust to environmental and genetic variation. A gene product that normally contributes to this robustness is termed a phenotypic capacitor. When a phenotypic capacitor fails, for example when challenged by a harsh environment or mutation, the system becomes less robust and thus produces greater phenotypic variation. A functional phenotypic capacitor provides a mechanism by which hidden polymorphism can accumulate, whereas its failure provides a mechanism by which evolutionary change might be promoted. The primary example to date of a phenotypic capacitor is Hsp90, a molecular chaperone that targets a large set of signal transduction proteins. In both Drosophila and Arabidopsis, compromised Hsp90 function results in pleiotropic phenotypic effects dependent on the underlying genotype. For some traits, Hsp90 also appears to buffer stochastic variation, yet the relationship between environmental and genetic buffering remains an important unresolved question. We previously used simulations of knockout mutations in transcriptional networks to predict that many gene products would act as phenotypic capacitors. To test this prediction, we use high-throughput morphological phenotyping of individual yeast cells from single-gene deletion strains to identify gene products that buffer environmental variation in Saccharomyces cerevisiae. We find more than 300 gene products that, when absent, increase morphological variation. Overrepresented among these capacitors are gene products that control chromosome organization and DNA integrity, RNA elongation, protein modification, cell cycle, and response to stimuli such as stress. Capacitors have a high number of synthetic-lethal interactions but knockouts of these genes do not tend to cause severe decreases in growth rate. Each capacitor can be classified based on whether or not it is encoded by a gene with a paralog in the genome. Capacitors with a duplicate are highly connected in the protein–protein interaction network and show considerable divergence in expression from their paralogs. In contrast, capacitors encoded by singleton genes are part of highly interconnected protein clusters whose other members also tend to affect phenotypic variability or fitness. These results suggest that buffering and release of variation is a widespread phenomenon that is caused by incomplete functional redundancy at multiple levels in the genetic architecture. PMID:18986213

The dendroclimatic proxies from the northern Quebec taiga in the PAGES 2K network: recent advances and future developments.

NASA Astrophysics Data System (ADS)

Gennaretti, Fabio; Naulier, Maud; Arseneault, Dominique; Savard, Martine; Bégin, Christian; Boucher, Etienne; Bégin, Yves; Guiot, Joël

2016-04-01

Northeastern North America was historically underrepresented in the network of climate proxies used for climate reconstructions over the last two millennia. Indeed, in North America most high-resolution climate proxies are long tree-ring chronologies but, in Northeastern North America, these chronologies are highly challenging due to short tree longevity, high frequency and severity of wildfires and remoteness of many areas. Here, we will present the efforts accomplished during the last decade by our team in developing millennial-long tree-ring chronologies in the northern Quebec taiga. We sampled black spruce [Picea mariana (Mill.) B.S.P] subfossil tree remains naturally fallen in the littoral zone of six lakes to build six site-specific ring-width chronologies as well as two chronologies of stable isotope ratios (δ18O and δ13C in tree-ring cellulose). These chronologies, which are now included in the PAGES 2K network, were independently used to reconstruct summer temperature variations showing a well-expressed Medieval Climate Anomaly and the impact of volcanic and solar forcings at regional scale. We will also discuss non-climatic influences on these chronologies (i.e. wildfires and sampling height inconsistency), as well as the ongoing effort to extend the reconstructions in time to cover the last 2500 years. Finally, a new European funded project called MAIDEN-SPRUCE will be introduced. Within MAIDEN-SPRUCE, we will use a data-model approach to improve our understanding of the links between forests and climate over the last millennium. More specifically, we will adapt the process-based ecophysiological model MAIDENiso to investigate factors influencing the growth and underlying biogeochemical processes of black spruce. One of our objectives is to provide the first multi-proxy (ring widths and δ18O and δ13C in tree-ring cellulose) regional climate reconstruction in Eastern North America over the last millennium taking into account mechanistic rules, including nonlinear or threshold relationships.

HPTN 035 phase II/IIb randomised safety and effectiveness study of the vaginal microbicides BufferGel and 0.5% PRO 2000 for the prevention of sexually transmitted infections in women.

PubMed

Guffey, M Bradford; Richardson, Barbra; Husnik, Marla; Makanani, Bonus; Chilongozi, David; Yu, Elmer; Ramjee, Gita; Mgodi, Nyaradzo; Gomez, Kailazarid; Hillier, Sharon L; Karim, Salim Abdool

2014-08-01

To estimate the effectiveness of candidate microbicides BufferGel and 0.5% PRO 2000 Gel (P) (PRO 2000) for prevention of non-ulcerative sexually transmitted infections (STIs). Between 2005 and 2007, 3099 women were enrolled in HIV Prevention Trials Network (HPTN) protocol 035, a phase II/IIb evaluation of the safety and effectiveness of BufferGel and PRO 2000 for prevention of STIs, including Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT) and Trichomonas vaginalis (TV). Incidences of STIs were determined by study arm, and HRs of BufferGel and PRO 2000 versus placebo gel or no gel control groups were computed using discrete time Andersen-Gill proportional hazards model. The overall incidence rates were 1.6/100 person-years at risk (PYAR) for NG, 3.9/100 PYAR for CT and 15.3/100 PYAR for TV. For BufferGel versus placebo gel, HRs were 0.99 (95% CI 0.49 to 2.00), 1.00 (95% CI 0.64 to 1.57) and 0.95 (95% CI 0.71 to 1.25) for prevention of NG, CT and TV, respectively. For PRO 2000, HRs were 1.66 (95% CI 0.90 to 3.06), 1.16 (95% CI 0.76 to 1.79) and 1.18 (95% CI 0.90 to 1.53) for prevention of NG, CT and TV, respectively. The incidence of STIs was high during HIV Prevention Trials Network 035 despite provision of free condoms and comprehensive risk-reduction counselling, highlighting the need for effective STI prevention programmes in this population. Unfortunately, candidate microbicides BufferGel and PRO2000 had no protective effect against gonorrhoea, chlamydia or trichomoniasis. NCT00074425. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

New type of chimera and mutual synchronization of spatiotemporal structures in two coupled ensembles of nonlocally interacting chaotic maps

NASA Astrophysics Data System (ADS)

Bukh, Andrei; Rybalova, Elena; Semenova, Nadezhda; Strelkova, Galina; Anishchenko, Vadim

2017-11-01

We study numerically the dynamics of a network made of two coupled one-dimensional ensembles of discrete-time systems. The first ensemble is represented by a ring of nonlocally coupled Henon maps and the second one by a ring of nonlocally coupled Lozi maps. We find that the network of coupled ensembles can realize all the spatio-temporal structures which are observed both in the Henon map ensemble and in the Lozi map ensemble while uncoupled. Moreover, we reveal a new type of spatiotemporal structure, a solitary state chimera, in the considered network. We also establish and describe the effect of mutual synchronization of various complex spatiotemporal patterns in the system of two coupled ensembles of Henon and Lozi maps.

Spontaneous actin dynamics in contractile rings

NASA Astrophysics Data System (ADS)

Kruse, Karsten; Wollrab, Viktoria; Thiagarajan, Raghavan; Wald, Anne; Riveline, Daniel

Networks of polymerizing actin filaments are known to be capable to self-organize into a variety of structures. For example, spontaneous actin polymerization waves have been observed in living cells in a number of circumstances, notably, in crawling neutrophils and slime molds. During later stages of cell division, they can also spontaneously form a contractile ring that will eventually cleave the cell into two daughter cells. We present a framework for describing networks of polymerizing actin filaments, where assembly is regulated by various proteins. It can also include the effects of molecular motors. We show that the molecular processes driven by these proteins can generate various structures that have been observed in contractile rings of fission yeast and mammalian cells. We discuss a possible functional role of each of these patterns. The work was supported by Agence Nationale de la Recherche, France, (ANR-10-LABX-0030-INRT) and by Deutsche Forschungsgemeinschaft through SFB1027.

Annual-ring-type quasi-phase-matching crystal for generation of narrowband high-dimensional entanglement

NASA Astrophysics Data System (ADS)

Hua, Yi-Lin; Zhou, Zong-Quan; Liu, Xiao; Yang, Tian-Shu; Li, Zong-Feng; Li, Pei-Yun; Chen, Geng; Xu, Xiao-Ye; Tang, Jian-Shun; Xu, Jin-Shi; Li, Chuan-Feng; Guo, Guang-Can

2018-01-01

A photon pair can be entangled in many degrees of freedom such as polarization, time bins, and orbital angular momentum (OAM). Among them, the OAM of photons can be entangled in an infinite-dimensional Hilbert space which enhances the channel capacity of sharing information in a network. Twisted photons generated by spontaneous parametric down-conversion offer an opportunity to create this high-dimensional entanglement, but a photon pair generated by this process is typically wideband, which makes it difficult to interface with the quantum memories in a network. Here we propose an annual-ring-type quasi-phase-matching (QPM) crystal for generation of the narrowband high-dimensional entanglement. The structure of the QPM crystal is designed by tracking the geometric divergences of the OAM modes that comprise the entangled state. The dimensionality and the quality of the entanglement can be greatly enhanced with the annual-ring-type QPM crystal.

Method and apparatus for routing data in an inter-nodal communications lattice of a massively parallel computer system by dynamic global mapping of contended links

DOEpatents

Archer, Charles Jens [Rochester, MN; Musselman, Roy Glenn [Rochester, MN; Peters, Amanda [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Swartz, Brent Allen [Chippewa Falls, WI; Wallenfelt, Brian Paul [Eden Prairie, MN

2011-10-04

A massively parallel nodal computer system periodically collects and broadcasts usage data for an internal communications network. A node sending data over the network makes a global routing determination using the network usage data. Preferably, network usage data comprises an N-bit usage value for each output buffer associated with a network link. An optimum routing is determined by summing the N-bit values associated with each link through which a data packet must pass, and comparing the sums associated with different possible routes.

Isoscapes of tree-ring carbon-13 perform like meteorological networks in predicting regional precipitation patterns

NASA Astrophysics Data System (ADS)

del Castillo, Jorge; Aguilera, Mònica; Voltas, Jordi; Ferrio, Juan Pedro

2013-04-01

Stable isotopes in tree rings provide climatic information with annual resolution dating back for centuries or even millennia. However, deriving spatially explicit climate models from isotope networks remains challenging. Here we propose a methodology to model regional precipitation from carbon isotope discrimination (Δ13C) in tree rings by (1) building regional spatial models of Δ13C (isoscapes), and (2) deriving precipitation maps from 13C-isoscapes, taking advantage of the response of Δ13C to precipitation in seasonally-dry climates. As a case study, we modeled the spatial distribution of mean annual precipitation (MAP) in the northeastern Iberian Peninsula, a region with complex orography and climate (MAP=303-1086 mm). We compiled wood Δ13C data for two Mediterranean species that exhibit complementary responses to seasonal precipitation (Pinus halepensis Mill., N=38; Quercus ilex L.; N=44; pooling period: 1975-2008). By combining multiple regression and geostatistical interpolation, we generated one 13C-isoscape for each species. A spatial model of MAP was then built as the sum of two complementary maps of seasonal precipitation, each one derived from the corresponding 13C-isoscape (September-November from Q. ilex; December-August from P. halepensis). Our approach showed a predictive power for MAP (RMSE=84 mm) nearly identical to that obtained by interpolating data directly from a similarly dense network of meteorological stations (RMSE=80-83 mm, N=65), being only outperformed when using a much denser meteorological network (RMSE=56-57 mm, N=340). This method offers new avenues for modeling spatial variability of past precipitation, exploiting the large amount of information currently available from tree-ring networks. Acknowledgements: This work was funded by MC-ERG-246725 (FP7, EU) and AGL 2012-40039-C02-02 (MINECO, Spain). JdC and JPF are supported by FPI fellowship (MCINN) and Ramón y Cajal programme (RYC-2008-02050, MINECO), respectively.

Functional and anatomical dissociation between the orthographic lexicon and the orthographic buffer revealed in reading and writing Chinese characters by fMRI.

PubMed

Chen, Hsiang-Yu; Chang, Erik C; Chen, Sinead H Y; Lin, Yi-Chen; Wu, Denise H

2016-04-01

The contribution of orthographic representations to reading and writing has been intensively investigated in the literature. However, the distinction between neuronal correlates of the orthographic lexicon and the orthographic (graphemic) buffer has rarely been examined in alphabetic languages and never been explored in non-alphabetic languages. To determine whether the neural networks associated with the orthographic lexicon and buffer of logographic materials are comparable to those reported in the literature, the present fMRI experiment manipulated frequency and the stroke number of Chinese characters in the tasks of form judgment and stroke judgment, which emphasized the processing of character recognition and writing, respectively. It was found that the left fusiform gyrus exhibited higher activation when encountering low-frequency than high-frequency characters in both tasks, which suggested this region to be the locus of the orthographic lexicon that represents the knowledge of character forms. On the other hand, the activations in the posterior part of the left middle frontal gyrus and in the left angular gyrus were parametrically modulated by the stroke number of target characters only in the stroke judgment task, which suggested these regions to be the locus of the orthographic buffer that represents the processing of stroke sequence in writing. These results provide the first evidence for the functional and anatomical dissociation between the orthographic lexicon and buffer in reading and writing Chinese characters. They also demonstrate the critical roles of the left fusiform area and the frontoparietal network to the long-term and short-term representations of orthographic knowledge, respectively, across different orthographies. Copyright © 2016 Elsevier Inc. All rights reserved.

A fast low-power optical memory based on coupled micro-ring lasers

NASA Astrophysics Data System (ADS)

Hill, Martin T.; Dorren, Harmen J. S.; de Vries, Tjibbe; Leijtens, Xaveer J. M.; den Besten, Jan Hendrik; Smalbrugge, Barry; Oei, Yok-Siang; Binsma, Hans; Khoe, Giok-Djan; Smit, Meint K.

2004-11-01

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20ps with 5.5fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zhiying; Heller, Eric J.; Krems, Roman V.

We explore the collision dynamics of complex hydrocarbon molecules (benzene, coronene, adamantane, and anthracene) containing carbon rings in a cold buffer gas of {sup 3}He. For benzene, we present a comparative analysis of the fully classical and fully quantum calculations of elastic and inelastic scattering cross sections at collision energies between 1 and 10 cm{sup −1}. The quantum calculations are performed using the time-independent coupled channel approach and the coupled-states approximation. We show that the coupled-states approximation is accurate at collision energies between 1 and 20 cm{sup −1}. For the classical dynamics calculations, we develop an approach exploiting the rigiditymore » of the carbon rings and including low-energy vibrational modes without holonomic constraints. Our results illustrate the effect of the molecular shape and the vibrational degrees of freedom on the formation of long-lived resonance states that lead to low-temperature clustering.« less

Time Shared Optical Network (TSON): a novel metro architecture for flexible multi-granular services.

PubMed

Zervas, Georgios S; Triay, Joan; Amaya, Norberto; Qin, Yixuan; Cervelló-Pastor, Cristina; Simeonidou, Dimitra

2011-12-12

This paper presents the Time Shared Optical Network (TSON) as metro mesh network architecture for guaranteed, statistically-multiplexed services. TSON proposes a flexible and tunable time-wavelength assignment along with one-way tree-based reservation and node architecture. It delivers guaranteed sub-wavelength and multi-granular network services without wavelength conversion, time-slice interchange and optical buffering. Simulation results demonstrate high network utilization, fast service delivery, and low end-to-end delay on a contention-free sub-wavelength optical transport network. In addition, implementation complexity in terms of Layer 2 aggregation, grooming and optical switching has been evaluated. © 2011 Optical Society of America

Augmenting groundwater monitoring networks near landfills with slurry cutoff walls.

PubMed

Hudak, Paul F

2004-01-01

This study investigated the use of slurry cutoff walls in conjunction with monitoring wells to detect contaminant releases from a solid waste landfill. The 50 m wide by 75 m long landfill was oriented oblique to regional groundwater flow in a shallow sand aquifer. Computer models calculated flow fields and the detection capability of six monitoring networks, four including a 1 m wide by 50 m long cutoff wall at various positions along the landfill's downgradient boundaries and upgradient of the landfill. Wells were positioned to take advantage of convergent flow induced downgradient of the cutoff walls. A five-well network with no cutoff wall detected 81% of contaminant plumes originating within the landfill's footprint before they reached a buffer zone boundary located 50 m from the landfill's downgradient corner. By comparison, detection efficiencies of networks augmented with cutoff walls ranged from 81 to 100%. The most efficient network detected 100% of contaminant releases with four wells, with a centrally located, downgradient cutoff wall. In general, cutoff walls increased detection efficiency by delaying transport of contaminant plumes to the buffer zone boundary, thereby allowing them to increase in size, and by inducing convergent flow at downgradient areas, thereby funneling contaminant plumes toward monitoring wells. However, increases in detection efficiency were too small to offset construction costs for cutoff walls. A 100% detection efficiency was also attained by an eight-well network with no cutoff wall, at approximately one-third the cost of the most efficient wall-augmented network.

Satisfaction with support versus size of network: differential effects of social support on psychological distress in parents of pediatric cancer patients.

PubMed

Harper, Felicity W K; Peterson, Amy M; Albrecht, Terrance L; Taub, Jeffrey W; Phipps, Sean; Penner, Louis A

2016-05-01

This study examined the direct and buffering effects of social support on longer-term global psychological distress among parents coping with pediatric cancer. In both sets of analyses, we examined whether these effects depended on the dimension of social support provided (i.e., satisfaction with support versus size of support network). Participants were 102 parents of pediatric cancer patients. At study entry, parents reported their trait anxiety, depression, and two dimensions of their social support network (satisfaction with support and size of support network). Parents subsequently reported their psychological distress in 3- and 9-month follow-up assessments. Parents' satisfaction with support had a direct effect on longer-term psychological distress; satisfaction was negatively associated with distress at both follow-ups. In contrast, size of support network buffered (moderated) the impact of trait anxiety and depression on later distress. Parents with smaller support networks and higher levels of trait anxiety and depression at baseline had higher levels of psychological distress at both follow-ups; for parents with larger support networks, there was no relationship. Social support can attenuate psychological distress in parents coping with pediatric cancer; however, the nature of the effect depends on the dimension of support. Whereas interventions that focus on increasing satisfaction with social support may benefit all parents, at-risk parents will likely benefit from interventions that ensure they have an adequate number of support resources. Copyright © 2015 John Wiley & Sons, Ltd.

Satisfaction with support versus size of network: Differential effects of social support on psychological distress in parents of pediatric cancer patients

PubMed Central

Harper, Felicity W. K.; Peterson, Amy M.; Albrecht, Terrance L.; Taub, Jeffrey W.; Phipps, Sean; Penner, Louis A.

2016-01-01

Objective This study examined the direct and the buffering effects of social support on longer-term global psychological distress among parents coping with pediatric cancer. In both sets of analyses we examined whether these effects depended on the dimension of social support provided (i.e., satisfaction with support versus size of support network). Method Participants were 102 parents of pediatric cancer patients. At study entry, parents reported their trait anxiety, depression, and two dimensions of their social support network (satisfaction with support and size of support network). Parents subsequently reported their psychological distress in 3- and 9-month follow-up assessments. Results Parents’ satisfaction with support had a direct effect on longer-term psychological distress; satisfaction was negatively associated with distress at both follow-ups. In contrast, size of support network buffered (moderated) the impact of trait anxiety and depression on later distress. Parents with smaller support networks and higher levels of trait anxiety and depression at baseline had higher levels of psychological distress at both follow-ups; for parents with larger support networks, there was no relationship. Conclusion Social support can attenuate psychological distress in parents coping with pediatric cancer; however, the nature of the effect depends on the dimension of support. Whereas, interventions that focus on increasing satisfaction with social support may benefit all parents, at-risk parents will likely benefit from interventions that ensure they have an adequate number of support resources. PMID:27092714

ER-PM Contacts Define Actomyosin Kinetics for Proper Contractile Ring Assembly.

PubMed

Zhang, Dan; Bidone, Tamara C; Vavylonis, Dimitrios

2016-03-07

The cortical endoplasmic reticulum (ER), an elaborate network of tubules and cisternae [1], establishes contact sites with the plasma membrane (PM) through tethering machinery involving a set of conserved integral ER proteins [2]. The physiological consequences of forming ER-PM contacts are not fully understood. Here, we reveal a kinetic restriction role of ER-PM contacts over ring compaction process for proper actomyosin ring assembly in Schizosaccharomyces pombe. We show that fission yeast cells deficient in ER-PM contacts exhibit aberrant equatorial clustering of actin cables during ring assembly and are particularly susceptible to compromised actin filament crosslinking activity. Using quantitative image analyses and computer simulation, we demonstrate that ER-PM contacts function to modulate the distribution of ring components and to constrain their compaction kinetics. We propose that ER-PM contacts have evolved as important physical modulators to ensure robust ring assembly. Copyright © 2016 Elsevier Ltd. All rights reserved.

9-(3,4-Dimeth-oxy-phen-yl)-3,3,6,6-tetra-methyl-4,5,6,9-tetra-hydro-3H-xanthene-1,8(2H,7H)-dione.

PubMed

Mehdi, Sayed Hasan; Sulaiman, Othman; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-07-01

The asymmetric unit of the title xanthene compound, C(25)H(30)O(5), contains two mol-ecules in which the pyran ring and the dimeth-oxy-phenyl ring are nearly perpendicular to one another [dihedral angles = 86.81 (8) and 84.45 (9)°]. One of the meth-oxy groups in one mol-ecule is twisted away from the phenyl ring [C-O-C-C torsion angle = -103.40 (16)°]. The pyran ring adopts a boat conformation whereas the two fused cyclo-hexane rings adopt envelope conformations in both mol-ecules. In the crystal, mol-ecules are linked into a three-dimensional network by C-H⋯O hydrogen bonds.

Mean Field Analysis of Stochastic Neural Network Models with Synaptic Depression

NASA Astrophysics Data System (ADS)

Yasuhiko Igarashi,; Masafumi Oizumi,; Masato Okada,

2010-08-01

We investigated the effects of synaptic depression on the macroscopic behavior of stochastic neural networks. Dynamical mean field equations were derived for such networks by taking the average of two stochastic variables: a firing-state variable and a synaptic variable. In these equations, the average product of thesevariables is decoupled as the product of their averages because the two stochastic variables are independent. We proved the independence of these two stochastic variables assuming that the synaptic weight Jij is of the order of 1/N with respect to the number of neurons N. Using these equations, we derived macroscopic steady-state equations for a network with uniform connections and for a ring attractor network with Mexican hat type connectivity and investigated the stability of the steady-state solutions. An oscillatory uniform state was observed in the network with uniform connections owing to a Hopf instability. For the ring network, high-frequency perturbations were shown not to affect system stability. Two mechanisms destabilize the inhomogeneous steady state, leading to two oscillatory states. A Turing instability leads to a rotating bump state, while a Hopf instability leads to an oscillatory bump state, which was previously unreported. Various oscillatory states take place in a network with synaptic depression depending on the strength of the interneuron connections.

Efficient spatial privacy preserving scheme for sensor network

NASA Astrophysics Data System (ADS)

Debnath, Ashmita; Singaravelu, Pradheepkumar; Verma, Shekhar

2013-03-01

The privacy of sensitive events observed by a wireless sensor networks (WSN) needs to be protected. Adversaries with the knowledge of sensor deployment and network protocols can infer the location of a sensed event by monitoring the communication from the sensors even when the messages are encrypted. Encryption provides confidentiality; however, the context of the event can used to breach the privacy of sensed objects. An adversary can track the trajectory of a moving object or determine the location of the occurrence of a critical event to breach its privacy. In this paper, we propose ring signature to obfuscate the spatial information. Firstly, the extended region of location of an event of interest as estimated from a sensor communication is presented. Then, the increase in this region of spatial uncertainty due to the effect of ring signature is determined. We observe that ring signature can effectively enhance the region of location uncertainty of a sensed event. As the event of interest can be situated anywhere in the enhanced region of uncertainty, its privacy against local or global adversary is ensured. Both analytical and simulation results show that induced delay and throughput are insignificant with negligible impact on the performance of a WSN.

Sensitivity of proxies on non-linear interactions in the climate system

PubMed Central

Schultz, Johannes A.; Beck, Christoph; Menz, Gunter; Neuwirth, Burkhard; Ohlwein, Christian; Philipp, Andreas

2015-01-01

Recent climate change is affecting the earth system to an unprecedented extent and intensity and has the potential to cause severe ecological and socioeconomic consequences. To understand natural and anthropogenic induced processes, feedbacks, trends, and dynamics in the climate system, it is also essential to consider longer timescales. In this context, annually resolved tree-ring data are often used to reconstruct past temperature or precipitation variability as well as atmospheric or oceanic indices such as the North Atlantic Oscillation (NAO) or the Atlantic Multidecadal Oscillation (AMO). The aim of this study is to assess weather-type sensitivity across the Northern Atlantic region based on two tree-ring width networks. Our results indicate that nonstationarities in superordinate space and time scales of the climate system (here synoptic- to global scale, NAO, AMO) can affect the climate sensitivity of tree-rings in subordinate levels of the system (here meso- to synoptic scale, weather-types). This scale bias effect has the capability to impact even large multiproxy networks and the ability of these networks to provide information about past climate conditions. To avoid scale biases in climate reconstructions, interdependencies between the different scales in the climate system must be considered, especially internal ocean/atmosphere dynamics. PMID:26686001

STED nanoscopy of the centrosome linker reveals a CEP68-organized, periodic rootletin network anchored to a C-Nap1 ring at centrioles.

PubMed

Vlijm, Rifka; Li, Xue; Panic, Marko; Rüthnick, Diana; Hata, Shoji; Herrmannsdörfer, Frank; Kuner, Thomas; Heilemann, Mike; Engelhardt, Johann; Hell, Stefan W; Schiebel, Elmar

2018-03-06

The centrosome linker proteins C-Nap1, rootletin, and CEP68 connect the two centrosomes of a cell during interphase into one microtubule-organizing center. This coupling is important for cell migration, cilia formation, and timing of mitotic spindle formation. Very little is known about the structure of the centrosome linker. Here, we used stimulated emission depletion (STED) microscopy to show that each C-Nap1 ring at the proximal end of the two centrioles organizes a rootletin ring and, in addition, multiple rootletin/CEP68 fibers. Rootletin/CEP68 fibers originating from the two centrosomes form a web-like, interdigitating network, explaining the flexible nature of the centrosome linker. The rootletin/CEP68 filaments are repetitive and highly ordered. Staggered rootletin molecules (N-to-N and C-to-C) within the filaments are 75 nm apart. Rootletin binds CEP68 via its C-terminal spectrin repeat-containing region in 75-nm intervals. The N-to-C distance of two rootletin molecules is ∼35 to 40 nm, leading to an estimated minimal rootletin length of ∼110 nm. CEP68 is important in forming rootletin filaments that branch off centrioles and to modulate the thickness of rootletin fibers. Thus, the centrosome linker consists of a vast network of repeating rootletin units with C-Nap1 as ring organizer and CEP68 as filament modulator. Copyright © 2018 the Author(s). Published by PNAS.

Analysis of reliability for multi-ring interconnection of RPR networks

NASA Astrophysics Data System (ADS)

Liu, Jia; Jin, Depeng; Zeng, Lieguang; Li, Yong

2008-11-01

In this paper, the reliability and MTTF (Mean Time to Failure) for multi-ring RPR (Resilient Packet Ring) are calculated on the conditions of single-link failures, double-link failures and no failure, respectively. The parameters such as the total number of stations N, the number of the sub-rings R, and the distribution of Ni which represents the number of the stations in the i-th sub-ring (1<=i<=R) are contained in the formulas. The relationship between the value of the reliability/MTTF and the parameters N, R and Ni is analyzed. The result shows that reliability/MTTF of the RPR multi-rings is increasing while the variance of Ni is decreasing. It is also proved that the value of the reliability/MTTF is maximum when Ni=Nj ( i ≠j and 1<=i, j<=R) by using Lagrange multipliers method, i.e. the condition of the optimal reliability of multi-ring RPR is satisfied when var(Ni) =0.

Biogeochemical Cycles of Carbon and Sulfur on Early Earth (and on Mars?)

NASA Technical Reports Server (NTRS)

DesMarais, D. J.

2004-01-01

The physical and chemical interactions between the atmosphere, hydrosphere, geosphere and biosphere can be examined for elements such as carbon (C) and sulfur (S) that have played central roles for both life and the environment. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. These multiple roles of C and S interact across a network of elemental reservoirs interconnected by physical, chemical and biological processes. These networks are termed biogeochemical C and S cycles.

The buffering effect of tangible social support on financial stress: influence on psychological well-being and psychosomatic symptoms in a large sample of the adult general population.

PubMed

Åslund, Cecilia; Larm, Peter; Starrin, Bengt; Nilsson, Kent W

2014-09-28

Financial stress is an important source of distress and is related to poor mental and physical health outcomes. The present study investigated whether tangible social support could buffer the effect of financial stress on psychological and psychosomatic health. Two separate postal surveys were sent to random samples in five counties in Sweden in 2004 and 2008, with a total of 84 263 respondents. The questionnaires included questions about financial stress, tangible social support, psychosomatic symptoms, and psychological well-being (General Health Questionnaire-12). Individuals with high financial stress and low tangible social support had six to seven times increased odds ratios for low psychological well-being and many psychosomatic symptoms. By contrast, individuals with high financial stress and high tangible social support had only two to three times increased odds ratios for low psychological well-being and three to four times increased odds ratios for many psychosomatic symptoms, suggesting a buffering effect of tangible social support. Consistent with the buffering hypothesis, there were significant interactions between financial stress and social support, particularly in relation to low psychological well-being. Social support had its strongest effect at high levels of financial stress. The question whether the altering of our social networks may improve physical health is important for the prevention of ill health in people experiencing financial stress. Strengthening social networks may have the potential to influence health-care costs and improve quality of life.

9-(3,4-Dimeth-oxy-phen-yl)-3,4,5,6,7,9-hexa-hydroxanthene-1,8(2H)-dione.

PubMed

Mehdi, Sayed Hasan; Hashim, Rokiah; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-06-01

In the title compound, C(21)H(22)O(5), the mean planes of the pyran and dimeth-oxy-phenyl rings are nearly perpendicular to one another, with the dihedral angle between them being 88.21 (8)°. The pyran ring adopts a boat conformation whereas the two fused cyclo-hexane rings adopt envelope conformations. In the crystal, mol-ecules are linked into a three-dimensional network by inter-molecular C-H⋯O hydrogen bonds.

Ring-array processor distribution topology for optical interconnects

NASA Technical Reports Server (NTRS)

Li, Yao; Ha, Berlin; Wang, Ting; Wang, Sunyu; Katz, A.; Lu, X. J.; Kanterakis, E.

1992-01-01

The existing linear and rectangular processor distribution topologies for optical interconnects, although promising in many respects, cannot solve problems such as clock skews, the lack of supporting elements for efficient optical implementation, etc. The use of a ring-array processor distribution topology, however, can overcome these problems. Here, a study of the ring-array topology is conducted with an aim of implementing various fast clock rate, high-performance, compact optical networks for digital electronic multiprocessor computers. Practical design issues are addressed. Some proof-of-principle experimental results are included.

Algebraic model checking for Boolean gene regulatory networks.

PubMed

Tran, Quoc-Nam

2011-01-01

We present a computational method in which modular and Groebner bases (GB) computation in Boolean rings are used for solving problems in Boolean gene regulatory networks (BN). In contrast to other known algebraic approaches, the degree of intermediate polynomials during the calculation of Groebner bases using our method will never grow resulting in a significant improvement in running time and memory space consumption. We also show how calculation in temporal logic for model checking can be done by means of our direct and efficient Groebner basis computation in Boolean rings. We present our experimental results in finding attractors and control strategies of Boolean networks to illustrate our theoretical arguments. The results are promising. Our algebraic approach is more efficient than the state-of-the-art model checker NuSMV on BNs. More importantly, our approach finds all solutions for the BN problems.

A Case Study of Two NRL Pump Prototypes

DTIC Science & Technology

1996-01-01

n messages messages ACK Pump Low High ACK MA buffer Figure 1. The simpli ed Pump architecture The Pump (see...I C A T I O N S Y S T E M S E R VICES Application Soft wa re Figure 4. STOP security ring structure The security kernel provides basic system...A D Y PUMP_TIMEOUT M O V _ A V G RECORD_AVAILABLE Ack A c k Ac k or N ac k Ack or Nack Legend IPC msg FIFO msg Data msg Process Object FIFO

Contractile-Ring Assembly in Fission Yeast Cytokinesis: Recent Advances and New Perspectives

PubMed Central

Lee, I-Ju; Coffman, Valerie C.; Wu, Jian-Qiu

2017-01-01

The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast. PMID:22887981

Contractile-ring assembly in fission yeast cytokinesis: Recent advances and new perspectives.

PubMed

Lee, I-Ju; Coffman, Valerie C; Wu, Jian-Qiu

2012-10-01

The fission yeast Schizosaccharomyces pombe is an excellent model organism to study cytokinesis. Here, we review recent advances on contractile-ring assembly in fission yeast. First, we summarize the assembly of cytokinesis nodes, the precursors of a normal contractile ring. IQGAP Rng2 and myosin essential light chain Cdc4 are recruited by the anillin-like protein Mid1, followed by the addition of other cytokinesis node proteins. Mid1 localization on the plasma membrane is stabilized by interphase node proteins. Second, we discuss proteins and processes that contribute to the search, capture, pull, and release mechanism of contractile-ring assembly. Actin filaments nucleated by formin Cdc12, the motor activity of myosin-II, the stiffness of the actin network, and severing of actin filaments by cofilin all play essential roles in contractile-ring assembly. Finally, we discuss the Mid1-independent pathway for ring assembly, and the possible mechanisms underlying the ring maturation and constriction. Collectively, we provide an overview of the current understanding of contractile-ring assembly and uncover future directions in studying cytokinesis in fission yeast. Copyright © 2012 Wiley Periodicals, Inc.

Do residents’ perceptions of being well-placed and objective presence of local amenities match? A case study in West Central Scotland, UK

PubMed Central

2013-01-01

Background Recently there has been growing interest in how neighbourhood features, such as the provision of local facilities and amenities, influence residents’ health and well-being. Prior research has measured amenity provision through subjective measures (surveying residents’ perceptions) or objective (GIS mapping of distance) methods. The latter may provide a more accurate measure of physical access, but residents may not use local amenities if they do not perceive them as ‘local’. We believe both subjective and objective measures should be explored, and use West Central Scotland data to investigate correspondence between residents’ subjective assessments of how well-placed they are for everyday amenities (food stores, primary and secondary schools, libraries, pharmacies, public recreation), and objective GIS-modelled measures, and examine correspondence by various sub-groups. Methods ArcMap was used to map the postal locations of ‘Transport, Health and Well-being 2010 Study’ respondents (n = 1760), and the six amenities, and the presence/absence of each of them within various straight-line and network buffers around respondents’ homes was recorded. SPSS was used to investigate whether objective presence of an amenity within a specified buffer was perceived by a respondent as being well-placed for that amenity. Kappa statistics were used to test agreement between measures for all respondents, and by sex, age, social class, area deprivation, car ownership, dog ownership, walking in the local area, and years lived in current home. Results In general, there was poor agreement (Kappa <0.20) between perceptions of being well-placed for each facility and objective presence, within 800 m and 1000 m straight-line and network buffers, with the exception of pharmacies (at 1000 m straight-line) (Kappa: 0.21). Results varied between respondent sub-groups, with some showing better agreement than others. Amongst sub-groups, at 800 m straight-line buffers, the highest correspondence between subjective and objective measures was for pharmacies and primary schools, and at 1000 m, for pharmacies, primary schools and libraries. For road network buffers under 1000 m, agreement was generally poor. Conclusion Respondents did not necessarily regard themselves as well-placed for specific amenities when these amenities were present within specified boundaries around their homes, with some exceptions; the picture is not clear-cut with varying findings between different amenities, buffers, and sub-groups. PMID:23651734

Learning non-local dependencies.

PubMed

Kuhn, Gustav; Dienes, Zoltán

2008-01-01

This paper addresses the nature of the temporary storage buffer used in implicit or statistical learning. Kuhn and Dienes [Kuhn, G., and Dienes, Z. (2005). Implicit learning of nonlocal musical rules: implicitly learning more than chunks. Journal of Experimental Psychology-Learning Memory and Cognition, 31(6) 1417-1432] showed that people could implicitly learn a musical rule that was solely based on non-local dependencies. These results seriously challenge models of implicit learning that assume knowledge merely takes the form of linking adjacent elements (chunking). We compare two models that use a buffer to allow learning of long distance dependencies, the Simple Recurrent Network (SRN) and the memory buffer model. We argue that these models - as models of the mind - should not be evaluated simply by fitting them to human data but by determining the characteristic behaviour of each model. Simulations showed for the first time that the SRN could rapidly learn non-local dependencies. However, the characteristic performance of the memory buffer model rather than SRN more closely matched how people came to like different musical structures. We conclude that the SRN is more powerful than previous demonstrations have shown, but it's flexible learned buffer does not explain people's implicit learning (at least, the affective learning of musical structures) as well as fixed memory buffer models do.

Mechanical characteristics of beta sheet-forming peptide hydrogels are dependent on peptide sequence, concentration and buffer composition

PubMed Central

Müller, Michael; König, Finja; Meyer, Nina; Gattlen, Jasmin; Pieles, Uwe; Peters, Kirsten; Kreikemeyer, Bernd; Mathes, Stephanie; Saxer, Sina

2018-01-01

Self-assembling peptide hydrogels can be modified regarding their biodegradability, their chemical and mechanical properties and their nanofibrillar structure. Thus, self-assembling peptide hydrogels might be suitable scaffolds for regenerative therapies and tissue engineering. Owing to the use of various peptide concentrations and buffer compositions, the self-assembling peptide hydrogels might be influenced regarding their mechanical characteristics. Therefore, the mechanical properties and stability of a set of self-assembling peptide hydrogels, consisting of 11 amino acids, made from four beta sheet self-assembling peptides in various peptide concentrations and buffer compositions were studied. The formed self-assembling peptide hydrogels exhibited stiffnesses ranging from 0.6 to 205 kPa. The hydrogel stiffness was mostly affected by peptide sequence followed by peptide concentration and buffer composition. All self-assembling peptide hydrogels examined provided a nanofibrillar network formation. A maximum self-assembling peptide hydrogel dissolution of 20% was observed for different buffer solutions after 7 days. The stability regarding enzymatic and bacterial digestion showed less degradation in comparison to the self-assembling peptide hydrogel dissolution rate in buffer. The tested set of self-assembling peptide hydrogels were able to form stable scaffolds and provided a broad spectrum of tissue-specific stiffnesses that are suitable for a regenerative therapy. PMID:29657766

Plasticity in dendroclimatic response across the distribution range of Aleppo Pine (Pinus halepensis)

Treesearch

Martin de Luis; Katarina Cufar; Alfredo Di Filippo; Klemen Novak; Andreas Papadopoulos; Gianluca Piovesan; Cyrille B. K. Rathgeber; José Raventós; Miguel Angel Saz; Kevin T. Smith

2013-01-01

We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the...

Global ring satellite communications system for future broadband network

NASA Astrophysics Data System (ADS)

Iida, Takashi; Suzuki, Yoshiaki; Arimoto, Yoshinori; Akaishi, Akira

2005-04-01

The purpose of this paper is to examine a cost model of a global ring satellite communications system as a 2G-satellite (second generation Internet satellite) for the future Internet satellite, whose capacity is around 120 Gbps. The authors proposed the future needs of research and development of communications satellite for the next 30 years and also proposed the approach of three generations for the future Internet satellites. First, the paper reviews and updates the original proposal for the future needs of communications satellite, considering the recent development of the quantum communication technology. It also examines the communications satellite applicability for bridging the digital divide in the Asia-Oceania as an example. The paper clarifies this possibility of communications satellite by showing various relationships among Internet penetration, land area, population growth, etc. Second, the cost of the global ring satellite is examined. The user terminal is considered as a combination of an earth terminal and wireless local area network for a user community. This paper shows that the global ring satellite has a possibility of a good cost-competitiveness to the terrestrial system because of the global communications system can be configured only by satellite system.

Lattice topology dictates photon statistics.

PubMed

Kondakci, H Esat; Abouraddy, Ayman F; Saleh, Bahaa E A

2017-08-21

Propagation of coherent light through a disordered network is accompanied by randomization and possible conversion into thermal light. Here, we show that network topology plays a decisive role in determining the statistics of the emerging field if the underlying lattice is endowed with chiral symmetry. In such lattices, eigenmode pairs come in skew-symmetric pairs with oppositely signed eigenvalues. By examining one-dimensional arrays of randomly coupled waveguides arranged on linear and ring topologies, we are led to a remarkable prediction: the field circularity and the photon statistics in ring lattices are dictated by its parity while the same quantities are insensitive to the parity of a linear lattice. For a ring lattice, adding or subtracting a single lattice site can switch the photon statistics from super-thermal to sub-thermal, or vice versa. This behavior is understood by examining the real and imaginary fields on a lattice exhibiting chiral symmetry, which form two strands that interleave along the lattice sites. These strands can be fully braided around an even-sited ring lattice thereby producing super-thermal photon statistics, while an odd-sited lattice is incommensurate with such an arrangement and the statistics become sub-thermal.

Generating broadband vortex modes in ring-core fiber by using a plasmonic q-plate.

PubMed

Ye, Jingfu; Li, Yan; Han, Yanhua; Deng, Duo; Su, Xiaoya; Song, He; Gao, Jianmin; Qu, Shiliang

2017-08-15

A mode convertor was proposed and investigated for generating vortex modes in a ring-core fiber based on a plasmonic q-plate (PQP), which is composed of specially organized L-shaped resonator (LSR) arrays. A multicore fiber was used to transmit fundamental modes, and the LSR arrays were used to modulate phases of these fundamental modes. Behind the PQP, the transmitted fundamental modes with gradient phase distribution can be considered as the incident lights for generating broadband vortex modes in the ring-core fiber filter. The topological charges of generated vortex modes can be various by using an optical PQP with different q, and the chirality of the generated vortex mode can be controlled by the sign of q and handedness of the incident circularly polarized light. The operation bandwidth is 800 nm in the range of 1200-2000 nm, which covers six communication bands from the O band to the U band. The separation of vortex modes also was addressed by using a dual ring-core fiber. The mode convertor is of potential interest for connecting a traditional network and vortex communication network.

Analysis of random drop for gateway congestion control. M.S. Thesis

NASA Technical Reports Server (NTRS)

Hashem, Emam Salaheddin

1989-01-01

Lately, the growing demand on the Internet has prompted the need for more effective congestion control policies. Currently No Gateway Policy is used to relieve and signal congestion, which leads to unfair service to the individual users and a degradation of overall network performance. Network simulation was used to illustrate the character of Internet congestion and its causes. A newly proposed gateway congestion control policy, called Random Drop, was considered as a promising solution to the pressing problem. Random Drop relieves resource congestion upon buffer overflow by choosing a random packet from the service queue to be dropped. The random choice should result in a drop distribution proportional to the bandwidth distribution among all contending TCP connections, thus applying the necessary fairness. Nonetheless, the simulation experiments demonstrate several shortcomings with this policy. Because Random Drop is a congestion control policy, which is not applied until congestion has already occurred, it usually results in a high drop rate that hurts too many connections including well-behaved ones. Even though the number of packets dropped is different from one connection to another depending on the buffer utilization upon overflow, the TCP recovery overhead is high enough to neutralize these differences, causing unfair congestion penalties. Besides, the drop distribution itself is an inaccurate representation of the average bandwidth distribution, missing much important information about the bandwidth utilization between buffer overflow events. A modification of Random Drop to do congestion avoidance by applying the policy early was also proposed. Early Random Drop has the advantage of avoiding the high drop rate of buffer overflow. The early application of the policy removes the pressure of congestion relief and allows more accurate signaling of congestion. To be used effectively, algorithms for the dynamic adjustment of the parameters of Early Random Drop to suite the current network load must still be developed.

Vasoconstriction Potency Induced by Aminoamide Local Anesthetics Correlates with Lipid Solubility

PubMed Central

Sung, Hui-Jin; Ok, Seong-Ho; Sohn, Jin-Young; Son, Yong Hyeok; Kim, Jun Kyu; Lee, Soo Hee; Han, Jeong Yeol; Lim, Dong Hoon; Shin, Il-Woo; Lee, Heon-Keun; Chung, Young-Kyun; Choi, Mun-Jeoung; Sohn, Ju-Tae

2012-01-01

Aminoamide local anesthetics induce vasoconstriction in vivo and in vitro. The goals of this in vitro study were to investigate the potency of local anesthetic-induced vasoconstriction and to identify the physicochemical property (octanol/buffer partition coefficient, pKa, molecular weight, or potency) of local anesthetics that determines their potency in inducing isolated rat aortic ring contraction. Cumulative concentration-response curves to local anesthetics (levobupivacaine, ropivacaine, lidocaine, and mepivacaine) were obtained from isolated rat aorta. Regression analyses were performed to determine the relationship between the reported physicochemical properties of local anesthetics and the local anesthetic concentration that produced 50% (ED50) of the local anesthetic-induced maximum vasoconstriction. We determined the order of potency (ED50) of vasoconstriction among local anesthetics to be levobupivacaine > ropivacaine > lidocaine > mepivacaine. The relative importance of the independent variables that affect the vasoconstriction potency is octanol/buffer partition coefficient > potency > pKa > molecular weight. The ED50 in endothelium-denuded aorta negatively correlated with the octanol/buffer partition coefficient of local anesthetics (r2 = 0.9563; P < 0.001). The potency of the vasoconstriction in the endothelium-denuded aorta induced by local anesthetics is determined primarily by lipid solubility and, in part, by other physicochemical properties including potency and pKa. PMID:22778542

Robust Routing Protocol For Digital Messages

NASA Technical Reports Server (NTRS)

Marvit, Maclen

1994-01-01

Refinement of ditigal-message-routing protocol increases fault tolerance of polled networks. AbNET-3 is latest of generic AbNET protocols for transmission of messages among computing nodes. AbNET concept described in "Multiple-Ring Digital Communication Network" (NPO-18133). Specifically aimed at increasing fault tolerance of network in broadcast mode, in which one node broadcasts message to and receives responses from all other nodes. Communication in network of computers maintained even when links fail.

Versatile RED-based buffer management mechanism for the efficient support of internet traffic

NASA Astrophysics Data System (ADS)

Nelissen, Jordi; De Cnodder, Stefaan

1999-11-01

This paper presents an evaluation of various GFR (Guaranteed Frame Rate) implementation proposals. By means of extensive simulations performed in different network environments we compare two ATM Forum example implementations, namely the `simple FIFO-based GFR.2 implementation' and the `per-VC threshold and scheduling implementation'. The lessons learned from this study are as well applicable to non-ATM network technologies.

Ring Attractor Dynamics Emerge from a Spiking Model of the Entire Protocerebral Bridge.

PubMed

Kakaria, Kyobi S; de Bivort, Benjamin L

2017-01-01

Animal navigation is accomplished by a combination of landmark-following and dead reckoning based on estimates of self motion. Both of these approaches require the encoding of heading information, which can be represented as an allocentric or egocentric azimuthal angle. Recently, Ca 2+ correlates of landmark position and heading direction, in egocentric coordinates, were observed in the ellipsoid body (EB), a ring-shaped processing unit in the fly central complex (CX; Seelig and Jayaraman, 2015). These correlates displayed key dynamics of so-called ring attractors, namely: (1) responsiveness to the position of external stimuli; (2) persistence in the absence of external stimuli; (3) locking onto a single external stimulus when presented with two competitors; (4) stochastically switching between competitors with low probability; and (5) sliding or jumping between positions when an external stimulus moves. We hypothesized that ring attractor-like activity in the EB arises from reciprocal neuronal connections to a related structure, the protocerebral bridge (PB). Using recent light-microscopy resolution catalogs of neuronal cell types in the PB (Lin et al., 2013; Wolff et al., 2015), we determined a connectivity matrix for the PB-EB circuit. When activity in this network was simulated using a leaky-integrate-and-fire model, we observed patterns of activity that closely resemble the reported Ca 2+ phenomena. All qualitative ring attractor behaviors were recapitulated in our model, allowing us to predict failure modes of the putative PB-EB ring attractor and the circuit dynamics phenotypes of thermogenetic or optogenetic manipulations. Ring attractor dynamics emerged under a wide variety of parameter configurations, even including non-spiking leaky-integrator implementations. This suggests that the ring-attractor computation is a robust output of this circuit, apparently arising from its high-level network properties (topological configuration, local excitation and long-range inhibition) rather than fine-scale biological detail.

Comparative analysis of the effectiveness of three immunization strategies in controlling disease outbreaks in realistic social networks.

PubMed

Xu, Zhijing; Zu, Zhenghu; Zheng, Tao; Zhang, Wendou; Xu, Qing; Liu, Jinjie

2014-01-01

The high incidence of emerging infectious diseases has highlighted the importance of effective immunization strategies, especially the stochastic algorithms based on local available network information. Present stochastic strategies are mainly evaluated based on classical network models, such as scale-free networks and small-world networks, and thus are insufficient. Three frequently referred stochastic immunization strategies-acquaintance immunization, community-bridge immunization, and ring vaccination-were analyzed in this work. The optimal immunization ratios for acquaintance immunization and community-bridge immunization strategies were investigated, and the effectiveness of these three strategies in controlling the spreading of epidemics were analyzed based on realistic social contact networks. The results show all the strategies have decreased the coverage of the epidemics compared to baseline scenario (no control measures). However the effectiveness of acquaintance immunization and community-bridge immunization are very limited, with acquaintance immunization slightly outperforming community-bridge immunization. Ring vaccination significantly outperforms acquaintance immunization and community-bridge immunization, and the sensitivity analysis shows it could be applied to controlling the epidemics with a wide infectivity spectrum. The effectiveness of several classical stochastic immunization strategies was evaluated based on realistic contact networks for the first time in this study. These results could have important significance for epidemic control research and practice.

Apollo Ring Optical Switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maestas, J.H.

1987-03-01

An optical switch was designed, built, and installed at Sandia National Laboratories in Albuquerque, New Mexico, to facilitate the integration of two Apollo computer networks into a single network. This report presents an overview of the optical switch as well as its layout, switch testing procedure and test data, and installation.

Soliton quenching NLTL impulse circuit with a pulse forming network at the output

DOEpatents

McEwan, Thomas E.; Dallum, Gregory E.

1998-01-01

An impulse forming circuit is disclosed which produces a clean impulse from a nonlinear transmission line compressed step function without customary soliton ringing by means of a localized pulse shaping and differentiating network which shunts the nonlinear transmission line output to ground.

Sub-nanometer pore formation in single-molecule-thick polyurea molecular-sieving membrane: a computational study.

PubMed

Park, Seongjin; Lansac, Yves; Jang, Yun Hee

2018-06-07

A polymeric network of 1-(4-tritylphenyl)urea (TPU) built via layer-by-layer cross-linking polymerization has been proposed to be an excellent mesh equipped with single-molecule-thick pores (i.e., cyclic poly-TPU rings), which can sieve glucose (∼0.7 nm) out of its mixture with urea for hemodialysis applications. Monte Carlo search for the lowest-energy conformation of various sizes of poly-TPU rings unravels the origin of narrow pore size distribution, which is around the sizes of dimer and trimer rings (0.3-0.8 nm). Flexible rings larger than the dimer and trimer rings, in particular tetramer rings, prefer a twisted conformation in the shape of the infinity symbol (∞, which looks like two dimer rings joined together) locked by a hydrogen bond between diphenylurea linker groups facing each other. Translocation energy profiles across these TPU rings reveal their urea-versus-glucose sieving mechanism: glucose is either too large (to enter dimers and twisted tetramers) or too perfectly fit (to exit trimers), leaving only a dimer-sized free space in the ring, whereas smaller-sized urea and water pass through these effective dimer-sized rings (bare dimers, twisted tetramers, and glucose-filled trimers) without encountering a substantial energy barrier or trap.

2-(4-Hy-droxy-phen-yl)-1H-benzimidazol-3-ium chloride monohydrate.

PubMed

González-Padilla, Jazmin E; Rosales-Hernández, Martha Cecila; Padilla-Martínez, Itzia I; García-Báez, Efren V; Rojas-Lima, Susana

2013-01-01

The title mol-ecular salt, C13H11N2O(+)·Cl(-)·H2O, crystallizes as a monohydrate. In the cation, the phenol and benzimidazole rings are almost coplanar, making a dihedral angle of 3.18 (4)°. The chloride anion and benzimidazole cation are linked by two N(+)-H⋯Cl(-) hydrogen bonds, forming chains propagating along [010]. These chains are linked through O-H⋯Cl hydrogen bonds involving the water mol-ecule and the chloride anion, which form a diamond core, giving rise to the formation of two-dimensional networks lying parallel to (10-2). Two π-π inter-actions involving the imidazolium ring with the benzene and phenol rings [centroid-centroid distances = 3.859 (3) and 3.602 (3) Å, respectively], contribute to this second dimension. A strong O-H⋯O hydrogen bond involving the water mol-ecule and the phenol substituent on the benzimidazole unit links the networks, forming a three-dimensional structure.

RiPPAS: A Ring-Based Privacy-Preserving Aggregation Scheme in Wireless Sensor Networks

PubMed Central

Zhang, Kejia; Han, Qilong; Cai, Zhipeng; Yin, Guisheng

2017-01-01

Recently, data privacy in wireless sensor networks (WSNs) has been paid increased attention. The characteristics of WSNs determine that users’ queries are mainly aggregation queries. In this paper, the problem of processing aggregation queries in WSNs with data privacy preservation is investigated. A Ring-based Privacy-Preserving Aggregation Scheme (RiPPAS) is proposed. RiPPAS adopts ring structure to perform aggregation. It uses pseudonym mechanism for anonymous communication and uses homomorphic encryption technique to add noise to the data easily to be disclosed. RiPPAS can handle both sum() queries and min()/max() queries, while the existing privacy-preserving aggregation methods can only deal with sum() queries. For processing sum() queries, compared with the existing methods, RiPPAS has advantages in the aspects of privacy preservation and communication efficiency, which can be proved by theoretical analysis and simulation results. For processing min()/max() queries, RiPPAS provides effective privacy preservation and has low communication overhead. PMID:28178197

Master-slave mixed arrays for data-flow computations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, T.L.; Fisher, P.D.

1983-01-01

Control cells (masters) and computation cells (slaves) are mixed in regular geometric patterns to form reconfigurable arrays known as master-slave mixed arrays (MSMAS). Interconnections of the corners and edges of the hexagonal control cells and the edges of the hexagonal computation cells are used to construct synchronous and asynchronous communication networks, which support local computation and local communication. Data-driven computations result in self-directed ring pipelines within the MSMA, and composite data-flow computations are executed in a pipelined fashion. By viewing an MSMA as a computing network of tightly-linked ring pipelines, data-flow programs can be uniformly distributed over these pipelines formore » efficient resource utilisation. 9 references.« less

Missing Rings in Pinus halepensis – The Missing Link to Relate the Tree-Ring Record to Extreme Climatic Events

PubMed Central

Novak, Klemen; de Luis, Martin; Saz, Miguel A.; Longares, Luis A.; Serrano-Notivoli, Roberto; Raventós, Josep; Čufar, Katarina; Gričar, Jožica; Di Filippo, Alfredo; Piovesan, Gianluca; Rathgeber, Cyrille B. K.; Papadopoulos, Andreas; Smith, Kevin T.

2016-01-01

Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees to adverse environmental conditions. The demonstrated relationship of MR formation to ECE across this dendrochronological network in the Mediterranean basin shows the potential of MR analysis to reconstruct the history of past climatic extremes and to predict future forest dynamics in a changing climate. PMID:27303421

Missing Rings in Pinus halepensis - The Missing Link to Relate the Tree-Ring Record to Extreme Climatic Events.

PubMed

Novak, Klemen; de Luis, Martin; Saz, Miguel A; Longares, Luis A; Serrano-Notivoli, Roberto; Raventós, Josep; Čufar, Katarina; Gričar, Jožica; Di Filippo, Alfredo; Piovesan, Gianluca; Rathgeber, Cyrille B K; Papadopoulos, Andreas; Smith, Kevin T

2016-01-01

Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees to adverse environmental conditions. The demonstrated relationship of MR formation to ECE across this dendrochronological network in the Mediterranean basin shows the potential of MR analysis to reconstruct the history of past climatic extremes and to predict future forest dynamics in a changing climate.

5-Bromo-N-methyl­pyrimidin-2-amine

PubMed Central

Yang, Qi; Xu, Ning; Zhu, Kai; Lv, Xiaoping; Han, Ping-fang

2012-01-01

In the title mol­ecule, C5H6BrN3, the pyrimidine ring is essentially planar, with an r.m.s. deviation of 0.007 Å. The Br and N atoms substituted to the pyrimidine ring are coplanar with the ring [displacements = 0.032 (1) and 0.009 (5) Å, respectively], while the methyl C atom lies 0.100 (15) Å from this plane with a dihedral angle between the pyrimidine ring and the methyl­amine group of 4.5 (3)°. In the crystal, C—H⋯N, C—H⋯Br and N—H⋯N hydrogen bonds link the mol­ecules into a two-dimensional network in the (011) plane. PMID:22259398

Soliton quenching NLTL impulse circuit with a pulse forming network at the output

DOEpatents

McEwan, T.E.; Dallum, G.E.

1998-09-08

An impulse forming circuit is disclosed which produces a clean impulse from a nonlinear transmission line compressed step function without customary soliton ringing by means of a localized pulse shaping and differentiating network which shunts the nonlinear transmission line output to ground. 5 figs.

9-(3,4-Dimeth­oxy­phen­yl)-3,4,5,6,7,9-hexa­hydroxanthene-1,8(2H)-dione

PubMed Central

Mehdi, Sayed Hasan; Hashim, Rokiah; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-01-01

In the title compound, C21H22O5, the mean planes of the pyran and dimeth­oxy­phenyl rings are nearly perpendicular to one another, with the dihedral angle between them being 88.21 (8)°. The pyran ring adopts a boat conformation whereas the two fused cyclo­hexane rings adopt envelope conformations. In the crystal, mol­ecules are linked into a three-dimensional network by inter­molecular C—H⋯O hydrogen bonds. PMID:21754824

Simulating Local Area Network Protocols with the General Purpose Simulation System (GPSS)

DTIC Science & Technology

1990-03-01

generation 15 3.1.2 Frame delivery . 15 3.2 Model artifices 16 3.3 Model variables 17 3.4 Simulation results 18 4. EXTERNAL PROCEDURES USED IN SIMULATION 19...46 15. Token Ring: Frame generation process 47 16. Token Ring: Frame delivery process 48 17 . Token Ring: Mean transfer delay vs mean throughput 49...assumed to be zero were replaced by the maximum values specified in the ANSI 802.3 standard (viz &MI=6, &M2=3, &M3= 17 , &D1=18, &D2=3, &D4=4, &D7=3, and

Expanding Actin Rings Zipper the Mouse Embryo for Blastocyst Formation.

PubMed

Zenker, Jennifer; White, Melanie D; Gasnier, Maxime; Alvarez, Yanina D; Lim, Hui Yi Grace; Bissiere, Stephanie; Biro, Maté; Plachta, Nicolas

2018-04-19

Transformation from morula to blastocyst is a defining event of preimplantation embryo development. During this transition, the embryo must establish a paracellular permeability barrier to enable expansion of the blastocyst cavity. Here, using live imaging of mouse embryos, we reveal an actin-zippering mechanism driving this embryo sealing. Preceding blastocyst stage, a cortical F-actin ring assembles at the apical pole of the embryo's outer cells. The ring structure forms when cortical actin flows encounter a network of polar microtubules that exclude F-actin. Unlike stereotypical actin rings, the actin rings of the mouse embryo are not contractile, but instead, they expand to the cell-cell junctions. Here, they couple to the junctions by recruiting and stabilizing adherens and tight junction components. Coupling of the actin rings triggers localized myosin II accumulation, and it initiates a tension-dependent zippering mechanism along the junctions that is required to seal the embryo for blastocyst formation. Copyright © 2018 Elsevier Inc. All rights reserved.

Single Sided Messaging v. 0.6.6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curry, Matthew Leon; Farmer, Matthew Shane; Hassani, Amin

Single-Sided Messaging (SSM) is a portable, multitransport networking library that enables applications to leverage potential one-sided capabilities of underlying network transports. It also provides desirable semantics that services for highperformance, massively parallel computers can leverage, such as an explicit cancel operation for pending transmissions, as well as enhanced matching semantics favoring large numbers of buffers attached to a single match entry. This release supports TCP/IP, shared memory, and Infiniband.

Yeast Phenomics: An Experimental Approach for Modeling Gene Interaction Networks that Buffer Disease

PubMed Central

Hartman, John L.; Stisher, Chandler; Outlaw, Darryl A.; Guo, Jingyu; Shah, Najaf A.; Tian, Dehua; Santos, Sean M.; Rodgers, John W.; White, Richard A.

2015-01-01

The genome project increased appreciation of genetic complexity underlying disease phenotypes: many genes contribute each phenotype and each gene contributes multiple phenotypes. The aspiration of predicting common disease in individuals has evolved from seeking primary loci to marginal risk assignments based on many genes. Genetic interaction, defined as contributions to a phenotype that are dependent upon particular digenic allele combinations, could improve prediction of phenotype from complex genotype, but it is difficult to study in human populations. High throughput, systematic analysis of S. cerevisiae gene knockouts or knockdowns in the context of disease-relevant phenotypic perturbations provides a tractable experimental approach to derive gene interaction networks, in order to deduce by cross-species gene homology how phenotype is buffered against disease-risk genotypes. Yeast gene interaction network analysis to date has revealed biology more complex than previously imagined. This has motivated the development of more powerful yeast cell array phenotyping methods to globally model the role of gene interaction networks in modulating phenotypes (which we call yeast phenomic analysis). The article illustrates yeast phenomic technology, which is applied here to quantify gene X media interaction at higher resolution and supports use of a human-like media for future applications of yeast phenomics for modeling human disease. PMID:25668739

An overview of SAFENET and its implications for aerospace applications

NASA Technical Reports Server (NTRS)

Collins, George C.; Bown, Rodney L.

1991-01-01

The survivable, adaptable fiber optic embeddable network (SAFENET) is a draft standard for local area networking (LAN) developed by the Navy which, when adopted, will become a military standard. The standard is being developed for procurement specifications of computer resources to be used on ships and aircraft and has some of the real-time concerns that network standards for space vehicles have. Architecture and survivability are considered. It is noted that the token-ring LAN must implement the IEEE 802.5 recommended practice for dual ring reconfiguration, which is currently being reviewed for inclusion into the IEEE standard. A trunk coupling unit is used at each station to isolate a station from the ring in case of failure. Up to five stations can be bypassed in this fashion. Communication architecture has an OSI profile but differs from the standard concept of the seven layers by allowing alternate suits and breaking the layers into three groupings of services to allow for physical interfacing. It also provides several paths, even if only one profile is used. Management and synchronization protocols are discussed and security issues are addressed. Implications for aerospace applications are considered and it is projected that interoperability with the Navy and other U.S. Government systems may require SAFENET specifications for NASA systems.

Solace in solidarity: Disability friendship networks buffer well-being.

PubMed

Silverman, Arielle M; Molton, Ivan R; Smith, Amanda E; Jensen, Mark P; Cohen, Geoffrey L

2017-11-01

To determine whether having friends who share one's disability experiences is associated with higher well-being, and whether these friendships buffer well-being from disability-related stressors. Research Method/Design: In 2 cross-sectional studies, adults with long-term physical disabilities identified close friends who shared their diagnosis. We assessed well-being as a function of the number of friends that participants identified in each group. Study 1 included 71 adults with legal blindness living in the United States, while Study 2 included 1,453 adults in the United States with either muscular dystrophy (MD), multiple sclerosis (MS), post-polio syndrome (PPS), or spinal cord injury (SCI). In Study 1, having more friends sharing a blindness diagnosis was associated with higher life satisfaction, even controlling for the number of friends who were not blind. In Study 2, Participants with more friends sharing their diagnosis reported higher quality of life and satisfaction with social role participation. Participants with more friends sharing their diagnosis also showed and attenuated associations between the severity of their functional impairment and their quality of life and social role satisfaction, suggesting that their friendships buffered the impact of their functional impairment on well-being. Participants reporting more friends with any physical disability showed similar benefits. Friends with disabilities can offer uniquely important informational and emotional support resources that buffer the impact of a functional impairment on well-being. Psychosocial interventions should help people with long-term disabilities build their peer support networks. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Habitat Suitability analysis of Koklass (Pucrasia macrolopha) Pheasant in Churdhar Wildlife Sanctuary of Himachal Pradesh, India using Geospatial Technology

NASA Astrophysics Data System (ADS)

Eliza, K.; Sarma, K.

2014-12-01

Pheasants are at the brink of destruction due to degradation of forests, environmental pollution, climatic changes and extensive hunting of wild floras and faunas.The problem is more acute in the developing countries where wildlife and biodiversity conservation are often less prioritized due to more pressing demands of food security and poverty alleviation. Koklass Pheasant (Pucrasia macrolopha) species is distributed from Afghanistan and Pakistan in the east along the Himalayas to southeastern Tibet, western China and southeastern Mongolia.This species is grouped under endangered species in Red Data Book of Zoological Survey of India and also classified as least concern species according to IUCN Red List of Threatened Species.Conservation biologists and managers need a range of both classical analyses and specific modern tools to face the increasing threats to biodiversity. Among these tools, habitat-suitability modeling has recently emerged as a relevant technique to assess global impacts to define wide conservation priorities.The present study is carried out using remote sensing satellite imagery and GIS modeling technique for assessing habitat suitability of Koklass Pheasants and finding out the habitat factors influencing the Koklass distribution in Churdhar Wildlife Sanctuary, India. Effective management and conservation of wildlife populations and their habitats largely depend on our ability to understand and predict species-habitat interactions. Different thematic maps viz., land use/cover, forest types, drainage buffer, multiple ring buffers of sighting locations and multiple ring buffers of roads have been prepared to support the objective of the study. The Weighted Overlay Analysis model is used for identifying different potential areas of habitat for this endangered species. The most suitable area for Koklass Pheasant within the Wildlife Sanctuary is found to be about 23.8 percent of the total area which is due to favourable habitat conditions for the survival of the species. The moderately high, moderate and least suitable areas come about 45.4, 24.9 and 5.9 percent, respectively. Identification of habitat potential areas for Koklass Pheasant species could be considered as one of the most important steps towards the conservation and management.

9-(3,4-Dimeth­oxy­phen­yl)-3,3,6,6-tetra­methyl-4,5,6,9-tetra­hydro-3H-xanthene-1,8(2H,7H)-dione

PubMed Central

Mehdi, Sayed Hasan; Sulaiman, Othman; Ghalib, Raza Murad; Yeap, Chin Sing; Fun, Hoong-Kun

2011-01-01

The asymmetric unit of the title xanthene compound, C25H30O5, contains two mol­ecules in which the pyran ring and the dimeth­oxy­phenyl ring are nearly perpendicular to one another [dihedral angles = 86.81 (8) and 84.45 (9)°]. One of the meth­oxy groups in one mol­ecule is twisted away from the phenyl ring [C—O—C—C torsion angle = −103.40 (16)°]. The pyran ring adopts a boat conformation whereas the two fused cyclo­hexane rings adopt envelope conformations in both mol­ecules. In the crystal, mol­ecules are linked into a three-dimensional network by C—H⋯O hydrogen bonds. PMID:21837111

The two nerve rings of the hypostomal nervous system of Hydra vulgaris-an immunohistochemical analysis.

PubMed

Hufnagel, L A; Kass-Simon, G

2016-11-01

In Hydra vulgaris, physiological and pharmacological evidence exists for a hypostomal circumferential neuro-effector pathway that initiates ectodermal pacemaker activity at tentacular-hypostomal loci coordinating body and tentacle contractions. Here, we describe an ectodermal nerve ring that runs below and between the tentacles, and an anti-GABA B receptor antibody-labeled ring coincident with it. The location of this ring is consistent with the physiology of the hypostomal pacemaker systems of hydra. We also describe a distally located, ectodermal ring of nerve fibers that is not associated with anti-GABA B receptor antibody labeling. The neurites and cell bodies of sensory cells contribute to both rings. The location of the distal ring and its sensory cell neurites suggests an involvement in the behavior of the mouth. Between the two rings is a network of anastomosing sensory and ganglion cell bodies and their neurites. Phase contrast, darkfield, and antibody-labeled images reveal that the mouth of hydra comprises five or six epithelial folds whose endoderm extensively labels with anti-GABA B receptor antibody, suggesting that endodermal metabotrobic GABA receptors are also involved in regulating mouth behavior.

Near real-time traffic routing

NASA Technical Reports Server (NTRS)

Yang, Chaowei (Inventor); Xie, Jibo (Inventor); Zhou, Bin (Inventor); Cao, Ying (Inventor)

2012-01-01

A near real-time physical transportation network routing system comprising: a traffic simulation computing grid and a dynamic traffic routing service computing grid. The traffic simulator produces traffic network travel time predictions for a physical transportation network using a traffic simulation model and common input data. The physical transportation network is divided into a multiple sections. Each section has a primary zone and a buffer zone. The traffic simulation computing grid includes multiple of traffic simulation computing nodes. The common input data includes static network characteristics, an origin-destination data table, dynamic traffic information data and historical traffic data. The dynamic traffic routing service computing grid includes multiple dynamic traffic routing computing nodes and generates traffic route(s) using the traffic network travel time predictions.

Non-equilibrium physics of neural networks for leaning, memory and decision making: landscape and flux perspectives

NASA Astrophysics Data System (ADS)

Wang, Jin

Cognitive behaviors are determined by underlying neural networks. Many brain functions, such as learning and memory, can be described by attractor dynamics. We developed a theoretical framework for global dynamics by quantifying the landscape associated with the steady state probability distributions and steady state curl flux, measuring the degree of non-equilibrium through detailed balance breaking. We found the dynamics and oscillations in human brains responsible for cognitive processes and physiological rhythm regulations are determined not only by the landscape gradient but also by the flux. We found that the flux is closely related to the degrees of the asymmetric connections in neural networks and is the origin of the neural oscillations. The neural oscillation landscape shows a closed-ring attractor topology. The landscape gradient attracts the network down to the ring. The flux is responsible for coherent oscillations on the ring. We suggest the flux may provide the driving force for associations among memories. Both landscape and flux determine the kinetic paths and speed of decision making. The kinetics and global stability of decision making are explored by quantifying the landscape topography through the barrier heights and the mean first passage time. The theoretical predictions are in agreement with experimental observations: more errors occur under time pressure. We quantitatively explored two mechanisms of the speed-accuracy tradeoff with speed emphasis and further uncovered the tradeoffs among speed, accuracy, and energy cost. Our results show an optimal balance among speed, accuracy, and the energy cost in decision making. We uncovered possible mechanisms of changes of mind and how mind changes improve performance in decision processes. Our landscape approach can help facilitate an understanding of the underlying physical mechanisms of cognitive processes and identify the key elements in neural networks.

Wireless Sensor Network Quality of Service Improvement on Flooding Attack Condition

NASA Astrophysics Data System (ADS)

Hartono, R.; Widyawan; Wibowo, S. B.; Purnomo, A.; Hartatik

2018-03-01

There are two methods of building communication using wireless media. The first method is building a base infrastructure as an intermediary between users. Problems that arise on this type of network infrastructure is limited space to build any network physical infrastructure and also the cost factor. The second method is to build an ad hoc network between users who will communicate. On ad hoc network, each user must be willing to send data from source to destination for the occurrence of a communication. One of network protocol in Ad Hoc, Ad hoc on demand Distance Vector (AODV), has the smallest overhead value, easier to adapt to dynamic network and has small control message. One AODV protocol’s drawback is route finding process’ security for sending the data. In this research, AODV protocol is optimized by determining Expanding Ring Search (ERS) best value. Random topology is used with variation in the number of nodes: 25, 50, 75, 100, 125 and 150 with node’s speed of 10m/s in the area of 1000m x 1000m on flooding network condition. Parameters measured are Throughput, Packet Delivery Ratio, Average Delay and Normalized Routing Load. From the test results of AODV protocol optimization with best value of Expanding Ring Search (ERS), throughput increased by 5.67%, packet delivery ratio increased by 5.73%, and as for Normalized Routing Load decreased by 4.66%. ERS optimal value for each node’s condition depending on the number of nodes on the network.

A carrier sensed multiple access protocol for high data base rate ring networks

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, Kurt J.; Overstreet, C. Michael; Khanna, S.; Paterra, Frank

1990-01-01

The results of the study of a simple but effective media access protocol for high data rate networks are presented. The protocol is based on the fact that at high data rates networks can contain multiple messages simultaneously over their span, and that in a ring, nodes used to detect the presence of a message arriving from the immediate upstream neighbor. When an incoming signal is detected, the node must either abort or truncate a message it is presently sending. Thus, the protocol with local carrier sensing and multiple access is designated CSMA/RN. The performance of CSMA/RN with TTattempt and truncate is studied using analytic and simulation models. Three performance factors, wait or access time, service time and response or end-to-end travel time are presented. The service time is basically a function of the network rate, it changes by a factor of 1 between no load and full load. Wait time, which is zero for no load, remains small for load factors up to 70 percent of full load. Response time, which adds travel time while on the network to wait and service time, is mainly a function of network length, especially for longer distance networks. Simulation results are shown for CSMA/RN where messages are removed at the destination. A wide range of local and metropolitan area network parameters including variations in message size, network length, and node count are studied. Finally, a scaling factor based upon the ratio of message to network length demonstrates that the results, and hence, the CSMA/RN protocol, are applicable to wide area networks.

Optimal fold symmetry of LH2 rings on a photosynthetic membrane

PubMed Central

Cleary, Liam; Chen, Hang; Chuang, Chern; Silbey, Robert J.; Cao, Jianshu

2013-01-01

An intriguing observation of photosynthetic light-harvesting systems is the N-fold symmetry of light-harvesting complex 2 (LH2) of purple bacteria. We calculate the optimal rotational configuration of N-fold rings on a hexagonal lattice and establish two related mechanisms for the promotion of maximum excitation energy transfer (EET). (i) For certain fold numbers, there exist optimal basis cells with rotational symmetry, extendable to the entire lattice for the global optimization of the EET network. (ii) The type of basis cell can reduce or remove the frustration of EET rates across the photosynthetic network. We find that the existence of a basis cell and its type are directly related to the number of matching points S between the fold symmetry and the hexagonal lattice. The two complementary mechanisms provide selection criteria for the fold number and identify groups of consecutive numbers. Remarkably, one such group consists of the naturally occurring 8-, 9-, and 10-fold rings. By considering the inter-ring distance and EET rate, we demonstrate that this group can achieve minimal rotational sensitivity in addition to an optimal packing density, achieving robust and efficient EET. This corroborates our findings i and ii and, through their direct relation to S, suggests the design principle of matching the internal symmetry with the lattice order. PMID:23650366

Optimal fold symmetry of LH2 rings on a photosynthetic membrane.

PubMed

Cleary, Liam; Chen, Hang; Chuang, Chern; Silbey, Robert J; Cao, Jianshu

2013-05-21

An intriguing observation of photosynthetic light-harvesting systems is the N-fold symmetry of light-harvesting complex 2 (LH2) of purple bacteria. We calculate the optimal rotational configuration of N-fold rings on a hexagonal lattice and establish two related mechanisms for the promotion of maximum excitation energy transfer (EET). (i) For certain fold numbers, there exist optimal basis cells with rotational symmetry, extendable to the entire lattice for the global optimization of the EET network. (ii) The type of basis cell can reduce or remove the frustration of EET rates across the photosynthetic network. We find that the existence of a basis cell and its type are directly related to the number of matching points S between the fold symmetry and the hexagonal lattice. The two complementary mechanisms provide selection criteria for the fold number and identify groups of consecutive numbers. Remarkably, one such group consists of the naturally occurring 8-, 9-, and 10-fold rings. By considering the inter-ring distance and EET rate, we demonstrate that this group can achieve minimal rotational sensitivity in addition to an optimal packing density, achieving robust and efficient EET. This corroborates our findings i and ii and, through their direct relation to S, suggests the design principle of matching the internal symmetry with the lattice order.

Development of optical packet and circuit integrated ring network testbed.

PubMed

Furukawa, Hideaki; Harai, Hiroaki; Miyazawa, Takaya; Shinada, Satoshi; Kawasaki, Wataru; Wada, Naoya

2011-12-12

We developed novel integrated optical packet and circuit switch-node equipment. Compared with our previous equipment, a polarization-independent 4 × 4 semiconductor optical amplifier switch subsystem, gain-controlled optical amplifiers, and one 100 Gbps optical packet transponder and seven 10 Gbps optical path transponders with 10 Gigabit Ethernet (10GbE) client-interfaces were newly installed in the present system. The switch and amplifiers can provide more stable operation without equipment adjustments for the frequent polarization-rotations and dynamic packet-rate changes of optical packets. We constructed an optical packet and circuit integrated ring network testbed consisting of two switch nodes for accelerating network development, and we demonstrated 66 km fiber transmission and switching operation of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10GbE frames. Error-free (frame error rate < 1×10(-4)) operation was achieved with optical packets of various packet lengths and packet rates, and stable operation of the network testbed was confirmed. In addition, 4K uncompressed video streaming over OPS links was successfully demonstrated. © 2011 Optical Society of America

Conformity hinders the evolution of cooperation on scale-free networks

NASA Astrophysics Data System (ADS)

Peña, Jorge; Volken, Henri; Pestelacci, Enea; Tomassini, Marco

2009-07-01

We study the effects of conformity, the tendency of humans to imitate locally common behaviors, in the evolution of cooperation when individuals occupy the vertices of a graph and engage in the one-shot prisoner’s dilemma or the snowdrift game with their neighbors. Two different graphs are studied: rings (one-dimensional lattices with cyclic boundary conditions) and scale-free networks of the Barabási-Albert type. The proposed evolutionary-graph model is studied both by means of Monte Carlo simulations and an extended pair-approximation technique. We find improved levels of cooperation when evolution is carried on rings and individuals imitate according to both the traditional payoff bias and a conformist bias. More importantly, we show that scale-free networks are no longer powerful amplifiers of cooperation when fair amounts of conformity are introduced in the imitation rules of the players. Such weakening of the cooperation-promoting abilities of scale-free networks is the result of a less biased flow of information in scale-free topologies, making hubs more susceptible of being influenced by less-connected neighbors.

Chimeras in leaky integrate-and-fire neural networks: effects of reflecting connectivities

NASA Astrophysics Data System (ADS)

Tsigkri-DeSmedt, Nefeli Dimitra; Hizanidis, Johanne; Schöll, Eckehard; Hövel, Philipp; Provata, Astero

2017-07-01

The effects of attracting-nonlocal and reflecting connectivity are investigated in coupled Leaky Integrate-and-Fire (LIF) elements, which model the exchange of electrical signals between neurons. Earlier investigations have demonstrated that repulsive-nonlocal and hierarchical network connectivity can induce complex synchronization patterns and chimera states in systems of coupled oscillators. In the LIF system we show that if the elements are nonlocally linked with positive diffusive coupling on a ring network, the system splits into a number of alternating domains. Half of these domains contain elements whose potential stays near the threshold and they are interrupted by active domains where the elements perform regular LIF oscillations. The active domains travel along the ring with constant velocity, depending on the system parameters. When we introduce reflecting coupling in LIF networks unexpected complex spatio-temporal structures arise. For relatively extensive ranges of parameter values, the system splits into two coexisting domains: one where all elements stay near the threshold and one where incoherent states develop, characterized by multi-leveled mean phase velocity profiles.

Investigation of decadal-scale divergence in tree-ring density chronologies

NASA Astrophysics Data System (ADS)

Vaccaro, A.; Emile-Geay, J.; Anchukaitis, K. J.; Wang, J.

2013-12-01

Tree-ring data from certain forest sites at northern circumpolar latitudes and from some at higher elevation show an anomalous decrease in temperature-sensitivity of tree growth starting in the mid-20th century. This phenomenon, known as the ';divergence problem' (DP), leads to tree-ring reconstructions that underestimate the warming trend exhibited by instrumental measurements over recent decades (e.g. D'Arrigo et al. 2008). In a study conducted in 1998, Briffa et al. discovered a type of divergence wherein latewood density (MXD) chronologies from an early manifestation of the Schweingruber tree-ring dataset showed strong interannual correlation to summer temperature measurements, but increasing divergence between the decadal-scale trends of the tree-rings and temperature records during the second half of the 20th century. This low-frequency divergence suggests that although tree-rings may accurately trace year-to-year changes in temperature, they might not capture longer-term warming trends, making them unsuitable for reconstructions of long-term climate variations. There is reason to believe, however, that the divergence found by Briffa (1998) is at least partly due to detrending or related statistical issues (Esper et al. 2009). Herein, we will investigate the distribution of this decadal-scale ';Briffa-style' divergence to see if it is confined to the earlier chronologies in the Schweingruber dataset or if it is persistent throughout more recent tree-ring data as well. Following the methodology of previous DP investigations (e.g. Briffa et al. 1998), we will draw comparisons between a network of MXD data and instrumental temperature records over an early period (1850-1960) and a recent period (1961-2000) to detect decadal-scale divergence in recent decades. We will apply the Mann et al. 2009 (M09) style of RegEM reconstruction to the M09 dataset, with and without controlling for divergence, and also to a new tree-ring database assembled using strict, objective criteria, including most of the updated Schweingruber network. Other climate field reconstruction (CFR) methods as described by Wang et al. (2013) will be used on our new tree-ring network to check for robustness. The tree-ring data will be independently compared to instrumental temperature series derived from the GHCN-monthly, HadCRUT4, and the M09 infilled HadCRUT3v temperature datasets for cross-validation. Implications for large-scale temperature reconstructions of the Common Era will be discussed. Briffa, K.R., F. H. Schweingruber, P.D. Jones, T.J. Osborn, S.G. Shiyatov, and E.A. Vaganov (1998),Reduced sensitivity of recent tree-growth to temperature at high northern latitudes, Nature, 391, 678-682. D'Arrigo, R., R. Wilson, B. Liepert, and P. Cherubini (2008), On the ';Divergence Problem' in Northern Forests: A review of the tree-ring evidence and possible causes, GAPC, 60, 289-305. Esper, J. and D. Frank (2009), Divergence pitfalls in tree-ring research, Climate Change, 94, 261-266. Mann, M.E., Z. Zhang, M.K. Hughes, R.S. Bradley, S.K. Miller, S. Rutherford, and F. Ni (2009), Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia, PNAS, 105 (36) 13252-13257. Wang, J., J. Emile-Geay, D. Guillot, and J. E. Smerdon (2013), Evaluating climate field reconstruction techniques using improved emulations of real-world conditions. CPD, 9, 3015-3060.

Quantifying the success of improved forest management from dendrochronology: examples from North Ethiopia

NASA Astrophysics Data System (ADS)

Jacob, Miro; De Ridder, Maaike; Frankl, Amaury; Guyassa, Etefa; Beeckman, Hans; Nyssen, Jan

2014-05-01

The increasing environmental and human pressure on the vulnerable environment of the North Ethiopian highlands requires sustainable management to avoid further land degradation. High altitude forests play a key role in this environmental balance and are very important for local livelihoods. They function as a hygric buffer by capturing and storing rainfall, which reduces soil erosion and protects against flooding, landslides and rock fall. The hygric buffer effect of mountain forests also provides water for downstream sources and for agriculture in the surrounding lowlands. Improved understanding of the growing patterns, ring formation and forest structure of this afro-alpine high altitude Erica arborea L. forests is essential to improve sustainable forest management practices. This paper studies two mountain forests in the North Ethiopian Highlands under contrasting management conditions; Lib Amba of the Abune Yosef Mt. range (12°04'N, 39°22'E, 3993 m a.s.l.) which is completely protected since five years and Mt. Ferrah Amba (12°52'N, 39°30'E, 3939 m a.s.l.) which is still strongly influenced by anthropo-zoogenic impacts. Dendrochronological results from cambial marked stem discs show complex but annual growth ring formations that reflect these differences in anthropo-zoogenic pressure; Tree-ring width is significantly wider in Mt. Lib Amba. Improved insight in the growing pattern of Erica arborea L. forests is also given by monitoring of tree growth and seedling recruitment in experimental plots since 2012 and by studying the relation between tree growth and the geomorphology and soil thickness. Seedling recruitment and vegetation indices indicate that tree growth is significantly better in the protected forest of Lib Amba. One of the key elements for sustainable land management is the creation of forests at critical locations. Insight in the response of tree growth to different types of land management and different morphological conditions can help to identify these critical locations. But most importantly, dendrochronological results have proven to be a valuable tool for objective validation of the success of land management strategies on a short term.

Experimental Analysis and Computational Modeling of Network States and Drug Responses in the PI3K/Akt/mTOR Network

DTIC Science & Technology

2010-09-01

Fixation was in 2% formaldehyde, followed by permeabilization in 100% methanol at -20 C. Blocking and incubation with primary/secondary antibodies ...was performed in Odyssey blocking buffer (LICOR). Primary antibodies were obtained from Cell Signaling, BD Biosciences, and Santa Cruz...Biotechnology, and Alexa fluor 488-, 555-, or 647-conjugated secondary antibodies were obtained from Invitrogen. Data were collected using an Applied Precision

Analog Delta-Back-Propagation Neural-Network Circuitry

NASA Technical Reports Server (NTRS)

Eberhart, Silvio

1990-01-01

Changes in synapse weights due to circuit drifts suppressed. Proposed fully parallel analog version of electronic neural-network processor based on delta-back-propagation algorithm. Processor able to "learn" when provided with suitable combinations of inputs and enforced outputs. Includes programmable resistive memory elements (corresponding to synapses), conductances (synapse weights) adjusted during learning. Buffer amplifiers, summing circuits, and sample-and-hold circuits arranged in layers of electronic neurons in accordance with delta-back-propagation algorithm.

Differential Regulation of Cryptic Genetic Variation Shapes the Genetic Interactome Underlying Complex Traits.

PubMed

Yadav, Anupama; Dhole, Kaustubh; Sinha, Himanshu

2016-12-01

Cryptic genetic variation (CGV) refers to genetic variants whose effects are buffered in most conditions but manifest phenotypically upon specific genetic and environmental perturbations. Despite having a central role in adaptation, contribution of CGV to regulation of quantitative traits is unclear. Instead, a relatively simplistic architecture of additive genetic loci is known to regulate phenotypic variation in most traits. In this paper, we investigate the regulation of CGV and its implication on the genetic architecture of quantitative traits at a genome-wide level. We use a previously published dataset of biparental recombinant population of Saccharomyces cerevisiae phenotyped in 34 diverse environments to perform single locus, two-locus, and covariance mapping. We identify loci that have independent additive effects as well as those which regulate the phenotypic manifestation of other genetic variants (variance QTL). We find that whereas additive genetic variance is predominant, a higher order genetic interaction network regulates variation in certain environments. Despite containing pleiotropic loci, with effects across environments, these genetic networks are highly environment specific. CGV is buffered under most allelic combinations of these networks and perturbed only in rare combinations resulting in high phenotypic variance. The presence of such environment specific genetic networks is the underlying cause of abundant gene–environment interactions. We demonstrate that overlaying identified molecular networks on such genetic networks can identify potential candidate genes and underlying mechanisms regulating phenotypic variation. Such an integrated approach applied to human disease datasets has the potential to improve the ability to predict disease predisposition and identify specific therapeutic targets.

Differential Regulation of Cryptic Genetic Variation Shapes the Genetic Interactome Underlying Complex Traits

PubMed Central

Yadav, Anupama; Dhole, Kaustubh

2016-01-01

Cryptic genetic variation (CGV) refers to genetic variants whose effects are buffered in most conditions but manifest phenotypically upon specific genetic and environmental perturbations. Despite having a central role in adaptation, contribution of CGV to regulation of quantitative traits is unclear. Instead, a relatively simplistic architecture of additive genetic loci is known to regulate phenotypic variation in most traits. In this paper, we investigate the regulation of CGV and its implication on the genetic architecture of quantitative traits at a genome-wide level. We use a previously published dataset of biparental recombinant population of Saccharomyces cerevisiae phenotyped in 34 diverse environments to perform single locus, two-locus, and covariance mapping. We identify loci that have independent additive effects as well as those which regulate the phenotypic manifestation of other genetic variants (variance QTL). We find that whereas additive genetic variance is predominant, a higher order genetic interaction network regulates variation in certain environments. Despite containing pleiotropic loci, with effects across environments, these genetic networks are highly environment specific. CGV is buffered under most allelic combinations of these networks and perturbed only in rare combinations resulting in high phenotypic variance. The presence of such environment specific genetic networks is the underlying cause of abundant gene–environment interactions. We demonstrate that overlaying identified molecular networks on such genetic networks can identify potential candidate genes and underlying mechanisms regulating phenotypic variation. Such an integrated approach applied to human disease datasets has the potential to improve the ability to predict disease predisposition and identify specific therapeutic targets. PMID:28172852

The Second "Ring of Towers": Over-sampling the Mid Continent Intensive region CO2 mixing ratio?

NASA Astrophysics Data System (ADS)

Richardson, S.; Miles, N.; Davis, K.; Crosson, E.; Denning, S.; Zupanksi, D.; Uliasz, M.

2007-12-01

A central barrier preventing the scientific community from understanding the carbon balance of the continent is methodological; it is technically difficult to bridge the gap in spatial scales that exists between the detailed understanding of ecological processes that can be gathered via intensive local field study, and the overarching but mechanistically poor understanding of the global carbon cycle that is gained by analyzing the atmospheric CO2 budget. The NACP's Midcontinental Intensive (MCI) study seeks to bridge this gap by conducting a rigorous methodological test of our ability to measure the terrestrial carbon balance of the upper Midwest. A critical need in bridging this gap is increased data density. A primary goal of the project is to increase the regional atmospheric CO2 data density so that 1) atmospheric inversions can derive well-constrained regional ecosystem carbon flux estimates and 2) the trade off between data density and accuracy of the flux estimates can be determined quantitatively using field observations, thus providing guidance to future observational network designs. Our work adds a regional network of five communications-tower based atmospheric CO2 observations to the planned long-term atmospheric CO2 observing network (tall towers, flux towers and aircraft profiles) in the midcontinent intensive region. Measurements began in April-June 2007, If the measurements are shown to be spatially dense enough to over sample the CO2 mixing ratio, the experiment will provide an upper bounds on the density of measurements required to produce the most accurate flux possible with current atmospheric inversions. The five sites for "Ring 2" and deployment dates are Centerville, IA (Apr 07), Round Lake, MN (May 07), Kewanee, IL (Apr 07), Mead, NE (Apr 07), Galesville, WI (June 07). Two heights are sampled at each tower (30 m AGL and between 110 and 140 m AGL). More details are available at www.ring2.psu.edu. In addition, two systems in PSU's network of well-calibrated CO2 mixing ratio measurements deployed at Ameriflux towers are within the midcontinental region: Ozark, MO (30 m AGL) and Mead, NE (3-6 m AGL) (www.amerifluxco2.psu.edu). The instruments chosen for the Ring 2 deployment are Picarro Inc., Cavity Ring-Down Spectroscopy (CRDS) instruments. One advantage of the CRDS instruments is the reduced need for calibration compared to the systems used in PSU's Ameriflux CO2 network which are calibrated every four hours using four calibration tanks. Although the long-term stability is not exactly known, tests have shown accuracy to within 0.2 ppm on a monthly time scale without additional calibration. Preliminary results show spatial differences in daytime CO2 across the ring that are as large as 40 ppm, and highly variable in time. We will present observations and preliminary interpretation of these data.

Microstructural evaluation of strained multilayer InAsSb/InSb infrared detectors by transmission electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chadda, S.; Datye, A.; Dawson, L.R.

InSb/InAsSb strained layer superlattices (SLS) were grown on (001) InSb substrates by molecular beam epitaxy at 425 [degree]C. The active device consisted of an InAs[sub 0.15]Sb[sub 0.85]/InSb superlattice region embedded within a [ital p]-[ital i]-[ital n] junction. The large lattice mismatch between the active device and the substrate required the growth of a buffer. InAs[sub 0.15]Sb[sub 0.85]/InSb SLS, where the average As content was gradually increased, was used as a buffer. The buffer structure was varied to probe its microstructural effect on the capping device. Three distinct approaches (A, B, and C) were used to grow the buffer. Approach Amore » was a four-step buffer where the average content of As in the superlattice was increased in four equal composition steps. This approach led to a crystal with an extensive network of threading dislocations and microcracks. Approach B was to change the average composition in five equal composition steps, thereby decreasing the misfit at the interfaces between composition steps. This led to a decrease in the threading dislocation density but microscopic cracks were still evident. The last approach (C) was to employ migration enhanced epitaxy (MEE) for the growth of the five-step buffer. Samples grown by employing MEE revealed no microcracks but they contained a high density of unusual wiggly'' dislocations at the buffer/device interface. Detailed microstructural analysis by transmission electron microscopy is presented.« less

Volcano-induced regime shifts in millennial tree-ring chronologies from northeastern North America.

PubMed

Gennaretti, Fabio; Arseneault, Dominique; Nicault, Antoine; Perreault, Luc; Bégin, Yves

2014-07-15

Dated records of ice-cap growth from Arctic Canada recently suggested that a succession of strong volcanic eruptions forced an abrupt onset of the Little Ice Age between A.D. 1275 and 1300 [Miller GH, et al. (2012) Geophys Res Lett 39(2):L02708, 10.1029/2011GL050168]. Although this idea is supported by simulation experiments with general circulation models, additional support from field data are limited. In particular, the Northern Hemisphere network of temperature-sensitive millennial tree-ring chronologies, which principally comprises Eurasian sites, suggests that the strongest eruptions only caused cooling episodes lasting less than about 10 y. Here we present a new network of millennial tree-ring chronologies from the taiga of northeastern North America, which fills a wide gap in the network of the Northern Hemisphere's chronologies suitable for temperature reconstructions and supports the hypothesis that volcanoes triggered both the onset and the coldest episode of the Little Ice Age. Following the well-expressed Medieval Climate Anomaly (approximately A.D. 910-1257), which comprised the warmest decades of the last millennium, our tree-ring-based temperature reconstruction displays an abrupt regime shift toward lower average summer temperatures precisely coinciding with a series of 13th century eruptions centered around the 1257 Samalas event and closely preceding ice-cap expansion in Arctic Canada. Furthermore, the successive 1809 (unknown volcano) and 1815 (Tambora) eruptions triggered a subsequent shift to the coldest 40-y period of the last 1100 y. These results confirm that series of large eruptions may cause region-specific regime shifts in the climate system and that the climate of northeastern North America is especially sensitive to volcanic forcing.

Volcano-induced regime shifts in millennial tree-ring chronologies from northeastern North America

PubMed Central

Gennaretti, Fabio; Arseneault, Dominique; Nicault, Antoine; Perreault, Luc; Bégin, Yves

2014-01-01

Dated records of ice-cap growth from Arctic Canada recently suggested that a succession of strong volcanic eruptions forced an abrupt onset of the Little Ice Age between A.D. 1275 and 1300 [Miller GH, et al. (2012) Geophys Res Lett 39(2):L02708, 10.1029/2011GL050168]. Although this idea is supported by simulation experiments with general circulation models, additional support from field data are limited. In particular, the Northern Hemisphere network of temperature-sensitive millennial tree-ring chronologies, which principally comprises Eurasian sites, suggests that the strongest eruptions only caused cooling episodes lasting less than about 10 y. Here we present a new network of millennial tree-ring chronologies from the taiga of northeastern North America, which fills a wide gap in the network of the Northern Hemisphere's chronologies suitable for temperature reconstructions and supports the hypothesis that volcanoes triggered both the onset and the coldest episode of the Little Ice Age. Following the well-expressed Medieval Climate Anomaly (approximately A.D. 910–1257), which comprised the warmest decades of the last millennium, our tree-ring-based temperature reconstruction displays an abrupt regime shift toward lower average summer temperatures precisely coinciding with a series of 13th century eruptions centered around the 1257 Samalas event and closely preceding ice-cap expansion in Arctic Canada. Furthermore, the successive 1809 (unknown volcano) and 1815 (Tambora) eruptions triggered a subsequent shift to the coldest 40-y period of the last 1100 y. These results confirm that series of large eruptions may cause region-specific regime shifts in the climate system and that the climate of northeastern North America is especially sensitive to volcanic forcing. PMID:24982132

Improving Information Management at Mare Island Naval Shipyard.

DTIC Science & Technology

1987-03-01

copy reports [Ref. 8: pp. 1-41. C. PRIME TOKEN RING The prime ring is a token-type computer network linking five PRIME computers electronically . Each...the PRIME net are for news (a bulletin board), electronic mail, word processing, and data filing. d 4 o, " ,, " "." ’-" r...communications application) This is a group of general-purpose programs that includes word processing. electronic mail, and spreadsheet applications. Access is

N-Benzyl­pyridin-2-amine

PubMed Central

Wang, Jun; Dai, Chuntao; Nie, Jianhua

2010-01-01

In the crystal of the title compound, C12H12N2, inter­molecular N—H⋯N hydrogen bonds form rings of graph-set motif R 2 2(8) and C—H⋯π inter­actions further consolidate the dimers. Neighbouring dimers are further connected into a three-dimensional network by C—H⋯π inter­actions. The benzyl and pyridyl rings form a dihedral angle of 67.2 (1)° PMID:21589385

Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers [Nanoparticle Motion in Entangled Melts of Non-Concatenated Ring Polymers].

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ge, Ting; Kalathi, Jagannathan T.; Halverson, Jonathan D.

The motion of nanoparticles (NPs) in entangled melts of linear polymers and non-concatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a, and is related to the hopping diffusion of NPs in the entanglement network. In contrast tomore » the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled non-concatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers.« less

Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers [Nanoparticle Motion in Entangled Melts of Non-Concatenated Ring Polymers].

DOE PAGES

Ge, Ting; Kalathi, Jagannathan T.; Halverson, Jonathan D.; ...

2017-02-13

The motion of nanoparticles (NPs) in entangled melts of linear polymers and non-concatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a, and is related to the hopping diffusion of NPs in the entanglement network. In contrast tomore » the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled non-concatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers.« less

2-(4-Hy­droxy­phen­yl)-1H-benzimidazol-3-ium chloride monohydrate

PubMed Central

González-Padilla, Jazmin E.; Rosales-Hernández, Martha Cecila; Padilla-Martínez, Itzia I.; García-Báez, Efren V.; Rojas-Lima, Susana

2013-01-01

The title mol­ecular salt, C13H11N2O+·Cl−·H2O, crystallizes as a monohydrate. In the cation, the phenol and benzimidazole rings are almost coplanar, making a dihedral angle of 3.18 (4)°. The chloride anion and benzimidazole cation are linked by two N+—H⋯Cl− hydrogen bonds, forming chains propagating along [010]. These chains are linked through O—H⋯Cl hydrogen bonds involving the water mol­ecule and the chloride anion, which form a diamond core, giving rise to the formation of two-dimensional networks lying parallel to (10-2). Two π–π inter­actions involving the imidazolium ring with the benzene and phenol rings [centroid–centroid distances = 3.859 (3) and 3.602 (3) Å, respectively], contribute to this second dimension. A strong O—H⋯O hydrogen bond involving the water mol­ecule and the phenol substituent on the benzimidazole unit links the networks, forming a three-dimensional structure. PMID:24427105

Does the choice of neighbourhood supermarket access measure influence associations with individual-level fruit and vegetable consumption? A case study from Glasgow.

PubMed

Thornton, Lukar E; Pearce, Jamie R; Macdonald, Laura; Lamb, Karen E; Ellaway, Anne

2012-07-27

Previous studies have provided mixed evidence with regards to associations between food store access and dietary outcomes. This study examines the most commonly applied measures of locational access to assess whether associations between supermarket access and fruit and vegetable consumption are affected by the choice of access measure and scale. Supermarket location data from Glasgow, UK (n = 119), and fruit and vegetable intake data from the 'Health and Well-Being' Survey (n = 1041) were used to compare various measures of locational access. These exposure variables included proximity estimates (with different points-of-origin used to vary levels of aggregation) and density measures using three approaches (Euclidean and road network buffers and Kernel density estimation) at distances ranging from 0.4 km to 5 km. Further analysis was conducted to assess the impact of using smaller buffer sizes for individuals who did not own a car. Associations between these multiple access measures and fruit and vegetable consumption were estimated using linear regression models. Levels of spatial aggregation did not impact on the proximity estimates. Counts of supermarkets within Euclidean buffers were associated with fruit and vegetable consumption at 1 km, 2 km and 3 km, and for our road network buffers at 2 km, 3 km, and 4 km. Kernel density estimates provided the strongest associations and were significant at a distance of 2 km, 3 km, 4 km and 5 km. Presence of a supermarket within 0.4 km of road network distance from where people lived was positively associated with fruit consumption amongst those without a car (coef. 0.657; s.e. 0.247; p0.008). The associations between locational access to supermarkets and individual-level dietary behaviour are sensitive to the method by which the food environment variable is captured. Care needs to be taken to ensure robust and conceptually appropriate measures of access are used and these should be grounded in a clear a priori reasoning.

Does the choice of neighbourhood supermarket access measure influence associations with individual-level fruit and vegetable consumption? A case study from Glasgow

PubMed Central

2012-01-01

Background Previous studies have provided mixed evidence with regards to associations between food store access and dietary outcomes. This study examines the most commonly applied measures of locational access to assess whether associations between supermarket access and fruit and vegetable consumption are affected by the choice of access measure and scale. Method Supermarket location data from Glasgow, UK (n = 119), and fruit and vegetable intake data from the ‘Health and Well-Being’ Survey (n = 1041) were used to compare various measures of locational access. These exposure variables included proximity estimates (with different points-of-origin used to vary levels of aggregation) and density measures using three approaches (Euclidean and road network buffers and Kernel density estimation) at distances ranging from 0.4 km to 5 km. Further analysis was conducted to assess the impact of using smaller buffer sizes for individuals who did not own a car. Associations between these multiple access measures and fruit and vegetable consumption were estimated using linear regression models. Results Levels of spatial aggregation did not impact on the proximity estimates. Counts of supermarkets within Euclidean buffers were associated with fruit and vegetable consumption at 1 km, 2 km and 3 km, and for our road network buffers at 2 km, 3 km, and 4 km. Kernel density estimates provided the strongest associations and were significant at a distance of 2 km, 3 km, 4 km and 5 km. Presence of a supermarket within 0.4 km of road network distance from where people lived was positively associated with fruit consumption amongst those without a car (coef. 0.657; s.e. 0.247; p0.008). Conclusions The associations between locational access to supermarkets and individual-level dietary behaviour are sensitive to the method by which the food environment variable is captured. Care needs to be taken to ensure robust and conceptually appropriate measures of access are used and these should be grounded in a clear a priori reasoning. PMID:22839742

Quantitative structure-retention relationships applied to development of liquid chromatography gradient-elution method for the separation of sartans.

PubMed

Golubović, Jelena; Protić, Ana; Otašević, Biljana; Zečević, Mira

2016-04-01

QSRR are mathematically derived relationships between the chromatographic parameters determined for a representative series of analytes in given separation systems and the molecular descriptors accounting for the structural differences among the investigated analytes. Artificial neural network is a technique of data analysis, which sets out to emulate the human brain's way of working. The aim of the present work was to optimize separation of six angiotensin receptor antagonists, so-called sartans: losartan, valsartan, irbesartan, telmisartan, candesartan cilexetil and eprosartan in a gradient-elution HPLC method. For this purpose, ANN as a mathematical tool was used for establishing a QSRR model based on molecular descriptors of sartans and varied instrumental conditions. The optimized model can be further used for prediction of an external congener of sartans and analysis of the influence of the analyte structure, represented through molecular descriptors, on retention behaviour. Molecular descriptors included in modelling were electrostatic, geometrical and quantum-chemical descriptors: connolly solvent excluded volume non-1,4 van der Waals energy, octanol/water distribution coefficient, polarizability, number of proton-donor sites and number of proton-acceptor sites. Varied instrumental conditions were gradient time, buffer pH and buffer molarity. High prediction ability of the optimized network enabled complete separation of the analytes within the run time of 15.5 min under following conditions: gradient time of 12.5 min, buffer pH of 3.95 and buffer molarity of 25 mM. Applied methodology showed the potential to predict retention behaviour of an external analyte with the properties within the training space. Connolly solvent excluded volume, polarizability and number of proton-acceptor sites appeared to be most influential paramateres on retention behaviour of the sartans. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers

PubMed Central

2017-01-01

The motion of nanoparticles (NPs) in entangled melts of linear polymers and nonconcatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter d larger than the entanglement spacing a is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as d exceeds a and is related to the hopping diffusion of NPs in the entanglement network. In contrast to the NP motion in linear polymers, the motion of NPs with d > a in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient D decreases with increasing d much slower in entangled rings than in entangled linear chains. NP motion in entangled nonconcatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers. PMID:28392603

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring.

PubMed

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong; Gould, Kathleen L

2017-09-15

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0-80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80-160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160-350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function.

Nanoscale architecture of the Schizosaccharomyces pombe contractile ring

PubMed Central

McDonald, Nathan A; Lind, Abigail L; Smith, Sarah E; Li, Rong

2017-01-01

The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0–80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80–160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160–350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function. PMID:28914606

Positive Neighborhood Norms Buffer Ethnic Diversity Effects on Neighborhood Dissatisfaction, Perceived Neighborhood Disadvantage, and Moving Intentions.

PubMed

Van Assche, Jasper; Asbrock, Frank; Roets, Arne; Kauff, Mathias

2018-05-01

Positive neighborhood norms, such as strong local networks, are critical to people's satisfaction with, perceived disadvantage of, and intentions to stay in their neighborhood. At the same time, local ethnic diversity is said to be detrimental for these community outcomes. Integrating both frameworks, we tested whether the negative consequences of diversity occur even when perceived social norms are positive. Study 1 ( N = 1,760 German adults) showed that perceptions of positive neighborhood norms buffered against the effects of perceived diversity on moving intentions via neighborhood satisfaction and perceived neighborhood disadvantage. Study 2 ( N = 993 Dutch adults) replicated and extended this moderated mediation model using other characteristics of diversity (i.e., objective and estimated minority proportions). Multilevel analyses again revealed consistent buffering effects of positive neighborhood norms. Our findings are discussed in light of the ongoing public and political debate concerning diversity and social and communal life.

From Networks to Time Series

NASA Astrophysics Data System (ADS)

Shimada, Yutaka; Ikeguchi, Tohru; Shigehara, Takaomi

2012-10-01

In this Letter, we propose a framework to transform a complex network to a time series. The transformation from complex networks to time series is realized by the classical multidimensional scaling. Applying the transformation method to a model proposed by Watts and Strogatz [Nature (London) 393, 440 (1998)], we show that ring lattices are transformed to periodic time series, small-world networks to noisy periodic time series, and random networks to random time series. We also show that these relationships are analytically held by using the circulant-matrix theory and the perturbation theory of linear operators. The results are generalized to several high-dimensional lattices.

Modelling high data rate communication network access protocol

NASA Technical Reports Server (NTRS)

Khanna, S.; Foudriat, E. C.; Paterra, Frank; Maly, Kurt J.; Overstreet, C. Michael

1990-01-01

Modeling of high data rate communication systems is different from the low data rate systems. Three simulations were built during the development phase of Carrier Sensed Multiple Access/Ring Network (CSMA/RN) modeling. The first was a model using SIMCRIPT based upon the determination and processing of each event at each node. The second simulation was developed in C based upon isolating the distinct object that can be identified as the ring, the message, the node, and the set of critical events. The third model further identified the basic network functionality by creating a single object, the node which includes the set of critical events which occur at the node. The ring structure is implicit in the node structure. This model was also built in C. Each model is discussed and their features compared. It should be stated that the language used was mainly selected by the model developer because of his past familiarity. Further the models were not built with the intent to compare either structure or language but because the complexity of the problem and initial results contained obvious errors, so alternative models were built to isolate, determine, and correct programming and modeling errors. The CSMA/RN protocol is discussed in sufficient detail to understand modeling complexities. Each model is described along with its features and problems. The models are compared and concluding observations and remarks are presented.

Analysis of Online DBA Algorithm with Adaptive Sleep Cycle in WDM EPON

NASA Astrophysics Data System (ADS)

Pajčin, Bojan; Matavulj, Petar; Radivojević, Mirjana

2018-05-01

In order to manage Quality of Service (QoS) and energy efficiency in the optical access network, an online Dynamic Bandwidth Allocation (DBA) algorithm with adaptive sleep cycle is presented. This DBA algorithm has the ability to allocate an additional bandwidth to the end user within a single sleep cycle whose duration changes depending on the current buffers occupancy. The purpose of this DBA algorithm is to tune the duration of the sleep cycle depending on the network load in order to provide service to the end user without violating strict QoS requests in all network operating conditions.

A Raman and UV-Vis study of catecholamines oxidized with Mn(III)

NASA Astrophysics Data System (ADS)

Barreto, W. J.; Ponzoni, S.; Sassi, P.

1998-12-01

A UV-Vis and Raman spectroscopy study of three aminochromes generated through Mn 3+ oxidation of the dopamine, L-dopa and adrenaline molecules at physiological pH was performed. The UV-Vis spectra of the catecholamines oxidized using Mn 3+ in buffer solution at pH 7.2 show a band at ca. 300 nm, formed by two transitions at 280 nm and 300 nm assigned to an La and Lb transition respectively, and other at ca. 470 nm assigned to an n- π* transition localized in the carbonyl group. This assignment is suggested by the UV-Vis and Raman spectra of ortho-aminoquinone generated by MnO 2 oxidation of a dopamine aqueous acidic solution. The resonance Raman spectra of the three chromes at buffer pH 7.2 show a very similar feature and the most intense bands are observed in the spectral range 1100-1800 cm -1. The band around 1680 cm -1 for the three compounds is assigned to a ν(CO) stretching vibration, 1630 cm -1 to the ν(CC) ring mode, two bands at 1423, 1439 cm -1; 1427, 1438 cm -1 and 1456, 1475 cm -1 are assigned to a ν(CN +) vibration, for aminochrome, dopachrome and adrenochrome, respectively. The excitation profiles for the most intense bands for aminochrome and adrenochrome were obtained. The band assigned to the ν(CN +) present a red shift with respect to the visible band peak, however the band in adrenochrome at 1475 cm -1 shows a profile similar to ν(CO) and ν(CC) modes that reflects the methyl group effect on mixing this mode more effectively with the ν(CC) ring mode.

Psychobiological Mechanisms Underlying the Social Buffering of the HPA Axis: A Review of Animal Models and Human Studies across Development

PubMed Central

Hostinar, Camelia E.; Sullivan, Regina M.; Gunnar, Megan R.

2013-01-01

Discovering the stress-buffering effects of social relationships has been one of the major findings in psychobiology in the last century. However, an understanding of the underlying neurobiological and psychological mechanisms of this buffering is only beginning to emerge. An important avenue of this research concerns the neurocircuitry that can regulate the activity of the hypothalamic-pituitary-adrenocortical (HPA) axis. The present review is a translational effort aimed at integrating animal models and human studies of the social regulation of the HPA axis from infancy to adulthood, specifically focusing on the process that has been named social buffering. This process has been noted across species and consists of a dampened HPA axis stress response to threat or challenge that occurs with the presence or assistance of a conspecific. We describe aspects of the relevant underlying neurobiology when enough information exists and expose major gaps in our understanding across all domains of the literatures we aimed to integrate. We provide a working conceptual model focused on the role of oxytocinergic systems and prefrontal neural networks as two of the putative biological mediators of this process, and propose that the role of early experiences is critical in shaping later social buffering effects. This synthesis points to both general future directions and specific experiments that need to be conducted to build a more comprehensive model of the HPA social buffering effect across the lifespan that incorporates multiple levels of analysis: neuroendocrine, behavioral, and social. PMID:23607429

Cassini RSS occultation observations of density waves in Saturn's rings

NASA Astrophysics Data System (ADS)

McGhee, C. A.; French, R. G.; Marouf, E. A.; Rappaport, N. J.; Schinder, P. J.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Johnston, D.; Rochblatt, D.

2005-08-01

On May 3, 2005, the first of a series of eight nearly diametric occultations by Saturn's rings and atmosphere took place, observed by the Cassini Radio Science (RSS) team. Simultaneous high SNR measurements at the Deep Space Network (DSN) at S, X, and Ka bands (λ = 13, 3.6, and 0.9 cm) have provided a remarkably detailed look at the radial structure and particle scattering behavior of the rings. By virtue of the relatively large ring opening angle (B=-23.6o), the slant path optical depth of the rings was much lower than during the Voyager epoch (B=5.9o), making it possible to detect many density waves and other ring features in the Cassini RSS data that were lost in the noise in the Voyager RSS experiment. Ultimately, diffraction correction of the ring optical depth profiles will yield radial resolution as small as tens of meters for the highest SNR data. At Ka band, the Fresnel scale is only 1--1.5 km, and thus even without diffraction correction, the ring profiles show a stunning array of density waves. The A ring is replete with dozens of Pandora and Prometheus inner Lindblad resonance features, and the Janus 2:1 density wave in the B ring is revealed with exceptional clarity for the first time at radio wavelengths. Weaker waves are abundant as well, and multiple occultation chords sample a variety of wave phases. We estimate the surface mass density of the rings from linear density wave models of the weaker waves. For stronger waves, non-linear models are required, providing more accurate estimates of the wave dispersion relation, the ring surface mass density, and the angular momentum exchange between the rings and satellite. We thank the DSN staff for their superb support of these complex observations.

Circle of Care: Extending Beyond Primary Caregivers to Examine Collaborative Caretaking in Adolescent Development

PubMed Central

Margolis, Kathryn L.; Fosco, Gregory M.; Stormshak, Elizabeth A.

2013-01-01

In the contemporary family, which is increasingly shaped by multicultural influences, parents rarely are the sole caretakers of their children. To improve understanding of family dynamics, researchers must redefine caregiving networks to include multiple caregivers, such as extended family members. This study explored the influences of caregiving networks on youth depression by examining who youths perceived as caretakers, how many caretakers were in their networks, the youths’ connectedness with adults in their network, and harmony of relationships among adults within the network. Data from an ethnically diverse, urban sample of 180 middle school youths revealed participation of multiple caregivers for all groups, but ethnic differences existed in network composition. These differences in network composition are discussed within a socio-cultural context, considering how positive relationships with specific caregivers may buffer future depression. Longitudinal analyses confirmed the importance of positive relationships with caregiving networks for youth of color when predicting future depression. PMID:27453615

High-strain slide-ring shape-memory polycaprolactone-based polyurethane.

PubMed

Wu, Ruiqing; Lai, Jingjuan; Pan, Yi; Zheng, Zhaohui; Ding, Xiaobin

2018-06-06

To enable shape-memory polymer networks to achieve recoverable high deformability with a simultaneous high shape-fixity ratio and shape-recovery ratio, novel semi-crystalline slide-ring shape-memory polycaprolactone-based polyurethane (SR-SMPCLU) with movable net-points constructed by a topologically interlocked slide-ring structure was designed and fabricated. The SR-SMPCLU not only exhibited good shape fixity, almost complete shape recovery, and a fast shape-recovery speed, it also showed an outstanding recoverable high-strain capacity with 95.83% Rr under a deformation strain of 1410% due to the pulley effect of the topological slide-ring structure. Furthermore, the SR-SMPCLU system maintained excellent shape-memory performance with increasing the training cycle numbers at 45% and even 280% deformation strain. The effects of the slide-ring cross-linker content, deformation strain, and successive shape-memory cycles on the shape-memory performance were investigated. A possible mechanism for the shape-memory effect of the SR-SMPCLU system is proposed.

Multi-objective optimization of riparian buffer networks; valuing present and future benefits

EPA Science Inventory

Multi-objective optimization has emerged as a popular approach to support water resources planning and management. This approach provides decision-makers with a suite of management options which are generated based on metrics that represent different social, economic, and environ...

TCP performance in ATM networks: ABR parameter tuning and ABR/UBR comparisons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chien Fang; Lin, A.

1996-02-27

This paper explores two issues on TOP performance over ATM networks: ABR parameter tuning and performance comparison of binary mode ABR with enhanced UBR services. Of the fifteen parameters defined for ABR, two parameters dominate binary mode ABR performance: Rate Increase Factor (RIF) and Rate Decrease Factor (RDF). Using simulations, we study the effects of these two parameters on TOP over ABR performance. We compare TOP performance with different ABR parameter settings in terms of through-puts and fairness. The effects of different buffer sizes and LAN/WAN distances are also examined. We then compare TOP performance with the best ABR parametermore » setting with corresponding UBR service enhanced with Early Packet Discard and also with a fair buffer allocation scheme. The results show that TOP performance over binary mode ABR is very sensitive to parameter value settings, and that a poor choice of parameters can result in ABR performance worse than that of the much less expensive UBR-EPD scheme.« less

Performance Analysis of Modified Accelerative Preallocation MAC Protocol for Passive Star-Coupled WDMA Networks

NASA Astrophysics Data System (ADS)

Yun, Changho; Kim, Kiseon

2006-04-01

For the passive star-coupled wavelength-division multiple-access (WDMA) network, a modified accelerative preallocation WDMA (MAP-WDMA) media access control (MAC) protocol is proposed, which is based on AP-WDMA. To show the advantages of MAP-WDMA as an adequate MAC protocol for the network over AP-WDMA, the channel utilization, the channel-access delay, and the latency of MAP-WDMA are investigated and compared with those of AP-WDMA under various data traffic patterns, including uniform, quasi-uniform type, disconnected type, mesh type, and ring type data traffics, as well as the assumption that a given number of network stations is equal to that of channels, in other words, without channel sharing. As a result, the channel utilization of MAP-WDMA can be competitive with respect to that of AP-WDMA at the expense of insignificantly higher latency. Namely, if the number of network stations is small, MAP-WDMA provides better channel utilization for uniform, quasi-uniform-type, and disconnected-type data traffics at all data traffic loads, as well as for mesh and ring-type data traffics at low data traffic loads. Otherwise, MAP-WDMA only outperforms AP-WDMA for the first three data traffics at higher data traffic loads. In the aspect of channel-access delay, MAP-WDMA gives better performance than AP-WDMA, regardless of data traffic patterns and the number of network stations.

Cassini Radio Occultations of Saturn's Rings: Scattered Signal and Particle Sizes

NASA Astrophysics Data System (ADS)

Thomson, F.; Wong, K.; Marouf, E.; French, R.; Rappaport, N.; McGhee, C.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischman, D.; Goltz, G.; Johnston, D.; Rochblatt, D.

2005-08-01

Eight Cassini radio occultations of Saturn's rings were conducted from May 3 to September 5, 2005. During any given occultation, Cassini transmits Ka-, X-, and S-band sinusoidal signals (0.94, 3.6, and 13 cm-wavelength) through the rings. Spectral analysis of the perturbed signals received at stations of the Deep Space Network (DSN) reveals two distinct signal components. The first is the direct signal, a narrowband component representing the incident sinusoid emerging from the rings reduced in amplitude and changed in phase. The second is the scattered signal, a broadband component, representing near-forward scattering by ring particles. After reconstruction to remove diffraction effects, time history of the direct signal yields profiles of ring structure at resolution approaching ˜50 m. Of primary concern here is the broadband component. For the first time ever, clearly detectable scattered signals were observed at all three (Ka/X/S) bands. A single X/S radio occultation by Voyager 1 in 1980 detected scattered signal at X-band only, primarily because of the small ring opening angle B=5.9o at the time, compared with 19.1 ≤ B ≤ 23.6o for Cassini. Time histories of the observed spectra (spectrograms) and their dependence on wavelength provide important information about physical ring properties, including abundance of meter-size particles, particle crowding, clustering, spatial anisotropy, vertical ring profile and thickness. Cassini occultation orbits were optimized to map scattering by individual ring features into nearly non-overlapping spectral bands, allowing unambiguous identification of the contribution of ring features to the computed spectrograms. We present Ka/X/S spectrograms over the full extent of the ring system and relate their behavior to observed ring structure. The spectrograms imply presence of meters-size particles throughout the ring system. Preliminary results regarding the particle size distribution and vertical ring profile of selected ring features are presented. Contributions of personnel of the DSN are gratefully acknowledged.

The apoptotic microtubule network preserves plasma membrane integrity during the execution phase of apoptosis.

PubMed

Sánchez-Alcázar, José A; Rodríguez-Hernández, Angeles; Cordero, Mario D; Fernández-Ayala, Daniel J M; Brea-Calvo, Gloria; Garcia, Katherina; Navas, Plácido

2007-07-01

It has recently been shown that the microtubule cytoskeleton is reformed during the execution phase of apoptosis. We demonstrate that this microtubule reformation occurs in many cell types and under different apoptotic stimuli. We confirm that the apoptotic microtubule network possesses a novel organization, whose nucleation appears independent of conventional gamma-tubulin ring complex containing structures. Our analysis suggests that microtubules are closely associated with the plasma membrane, forming a cortical ring or cellular "cocoon". Concomitantly other components of the cytoskeleton, such as actin and cytokeratins disassemble. We found that colchicine-mediated disruption of apoptotic microtubule network results in enhanced plasma membrane permeability and secondary necrosis, suggesting that the reformation of a microtubule cytoskeleton plays an important role in preserving plasma membrane integrity during apoptosis. Significantly, cells induced to enter apoptosis in the presence of the pan-caspase inhibitor z-VAD, nevertheless form microtubule-like structures suggesting that microtubule formation is not dependent on caspase activation. In contrast we found that treatment with EGTA-AM, an intracellular calcium chelator, prevents apoptotic microtubule network formation, suggesting that intracellular calcium may play an essential role in the microtubule reformation. We propose that apoptotic microtubule network is required to maintain plasma membrane integrity during the execution phase of apoptosis.

Is the kinetoplast DNA a percolating network of linked rings at its critical point?

NASA Astrophysics Data System (ADS)

Michieletto, Davide; Marenduzzo, Davide; Orlandini, Enzo

2015-05-01

In this work we present a computational study of the kinetoplast genome, modelled as a large number of semiflexible unknotted loops, which are allowed to link with each other. As the DNA density increases, the systems shows a percolation transition between a gas of unlinked rings and a network of linked loops which spans the whole system. Close to the percolation transition, we find that the mean valency of the network, i.e. the average number of loops which are linked to any one loop, is around three, as found experimentally for the kinetoplast DNA (kDNA). Even more importantly, by simulating the digestion of the network by a restriction enzyme, we show that the distribution of oligomers, i.e. structures formed by a few loops which remain linked after digestion, quantitatively matches experimental data obtained from gel electrophoresis, provided that the density is, once again, close to the percolation transition. With respect to previous work, our analysis builds on a reduced number of assumptions, yet can still fully explain the experimental data. Our findings suggest that the kDNA can be viewed as a network of linked loops positioned very close to the percolation transition, and we discuss the possible biological implications of this remarkable fact.

Ring trial 2016 for Bluetongue virus detection by real-time RT-PCR in France.

PubMed

Sailleau, Corinne; Viarouge, Cyril; Breard, Emmanuel; Vitour, Damien; Zientara, Stephan

2017-05-01

Since the unexpected emergence of BTV-8 in Northern Europe and the incursion of BTV-8 and 1 in France in 2006-2007, molecular diagnosis has considerably evolved. Several real-time RT-PCR (rtRT-PCR) methods have been developed and published, and are currently being used in many countries across Europe for BTV detection and typing. In France, the national reference laboratory (NRL) for orbiviruses develops and validates 'ready-to-use' kits with private companies for viral RNA detection. The regional laboratories network that was set up to deal with a heavy demand for analyses has used these available kits. From 2007, ring tests were organized to monitor the performance of the French laboratories. This study presents the results of 63 regional laboratories in the ring trial organized in 2016. Blood samples were sent to the laboratories. Participants were asked to use the rtRT-PCR methods in place in their laboratory, for detection of all BTV serotypes and specifically BTV-8. The French regional laboratories are able to detect and genotype BTV in affected animals. Despite the use of several methods (i.e. RNA extraction and different commercial rtRT-PCRs), the network is homogeneous. The ring trial demonstrated that the French regional veterinary laboratories have reliable and robust BTV diagnostic tools for BTV genome detection.

Optical bio-sniffer for ethanol vapor using an oxygen-sensitive optical fiber.

PubMed

Mitsubayashi, Kohji; Kon, Takuo; Hashimoto, Yuki

2003-11-30

An optical bio-sniffer for ethanol was constructed by immobilizing alcohol oxidase (AOD) onto a tip of a fiber optic oxygen sensor with a tube-ring, using an oxygen sensitive ruthenium organic complex (excitation, 470 nm; fluorescent, 600 nm). A reaction unit for circulating buffer solution was applied to the tip of the device. After the experiment in the liquid phase, the sniffer-device was applied for gas analysis using a gas flow measurement system with a gas generator. The optical device was applied to detect the oxygen consumption induced by AOD enzymatic reaction with alcohol application. The sensor in the liquid phase was used to measure ethanol solution from 0.50 to 9.09 mmol/l. Then, the bio-sniffer was calibrated against ethanol vapor from 0.71 to 51.49 ppm with good gas-selectivity based on the AOD substrate specificity. The bio-sniffer with the reaction unit was also used to monitor the concentration change of gaseous ethanol by rinsing and cleaning the fiber tip and the enzyme membrane with buffer solution.

The EASTNET Project: Extending the Network of Climate-Sensitive Tree-Ring Chronologies From the Eastern United States for Reconstructing the Spatio-Temporal Characteristics of Climate and Drought Over the Past Millennium

NASA Astrophysics Data System (ADS)

Buckley, B. M.; Cook, E. R.

2002-12-01

Recently, a network of gridded PDSI reconstructions for the contiguous United States was produced, based on the available network of drought-sensitive tree-ring chronologies (Cook et al. 1999). Analyses were constrained to the common period of 1700 - 1979 due to the limitations of the available tree-ring data. While several chronologies from the western U.S. span 1,000 years or more, very few chronologies from the eastern U.S. covered even the past 500 years. The objective of this project, funded by the National Science Foundation's ESH program, is to extend the tree-ring chronology network from the eastern U.S. with chronologies spanning the past 500-1,000 years. This aim is being achieved by sampling in areas that have escaped the effects of development, logging and major disturbance such as fire. The two main target species are Thuja occidentalis (eastern white cedar) and Juniperus virginiana (eastern red cedar). The primary terrain types are on cliffs, rocky outcrops, and other areas that have been difficult to access. We have already developed chronologies from Wisconsin, New Hampshire, Pennsylvania, West Virginia, and Virginia that span from 500 to 1500 years. The temporal depth of these chronologies is being extended through the exploitation of "sub-fossil" wood found at these sites, in the form of standing-dead stems and downed and buried logs. We are also currently pursuing leads in Maine, Vermont, Massachusetts, Connecticut, New York, New Jersey Pennsylvania, Kentucky and North Carolina where old cedar trees have either been reported or where terrain types match criteria developed for this project. In this paper we discuss the current status of the network, and explore the spatio-temporal characteristics of climate and drought across the eastern US for the past 500 years and more. We use our preliminary network to explore the regional expression of climate anomalies such as drought. Our analyses so far demonstrates multicentennial variability suggestive of Medieval Warm Period (MWP) and Little Ice Age (LIA) type signatures from an eastern red cedar chronology from West Virginia that spans the past 1,500 years. This is the oldest chronology so far developed from this project, though we anticipate the development of several more millennial length time-series within the next year. References Cook, E.R., Meko, D.M., Stahle, D.W., and Cleaveland, M.K. 1999. Drought reconstructions for the continental United States. Journal of Climate 12:1145-1162.

Early childhood behavioral inhibition, adult psychopathology and the buffering effects of adolescent social networks: a twenty-year prospective study.

PubMed

Frenkel, Tahl I; Fox, Nathan A; Pine, Daniel S; Walker, Olga L; Degnan, Kathryn A; Chronis-Tuscano, Andrea

2015-10-01

We examined whether the temperament of behavioral inhibition is a significant marker for psychopathology in early adulthood and whether such risk is buffered by peer social networks. Participants (N = 165) were from a prospective study spanning the first two decades of life. Temperament was characterized during infancy and early childhood. Extent of involvement in peer social networks was measured during adolescence, and psychopathology was assessed in early adulthood. Latent Class Analyses generated comprehensive variables at each of three study time-points. Regressions assessed (a) the direct effect of early behavioral inhibition on adult psychopathology (b) the moderating effect of adolescent involvement in social peer networks on the link between temperamental risk and adult psychopathology. Stable behavioral inhibition in early childhood was negatively associated with adult mental health (R(2 ) = .07, p = .005, β = -.26), specifically increasing risk for adult anxiety disorders (R(2) = .04, p = .037, β = .19). These temperament-pathology relations were significantly moderated by adolescent peer group social involvement and network size (Total R(2) = .13, p = .027, β = -.22). Temperament predicted heightened risk for adult anxiety when adolescent social involvement was low (p = .002, β = .43), but not when adolescent social involvement was high. Stable behavioral inhibition throughout early childhood is a risk factor for adult anxiety disorders and interacts with adolescent social involvement to moderate risk. This is the first study to demonstrate the critical role of adolescent involvement in socially active networks in moderating long-lasting temperamental risk over the course of two decades, thus informing prevention/intervention approaches. © 2015 Association for Child and Adolescent Mental Health.

Achieving Congestion Mitigation Using Distributed Power Control for Spectrum Sensor Nodes in Sensor Network-Aided Cognitive Radio Ad Hoc Networks

PubMed Central

Zhuo, Fan; Duan, Hucai

2017-01-01

The data sequence of spectrum sensing results injected from dedicated spectrum sensor nodes (SSNs) and the data traffic from upstream secondary users (SUs) lead to unpredictable data loads in a sensor network-aided cognitive radio ad hoc network (SN-CRN). As a result, network congestion may occur at a SU acting as fusion center when the offered data load exceeds its available capacity, which degrades network performance. In this paper, we present an effective approach to mitigate congestion of bottlenecked SUs via a proposed distributed power control framework for SSNs over a rectangular grid based SN-CRN, aiming to balance resource load and avoid excessive congestion. To achieve this goal, a distributed power control framework for SSNs from interior tier (IT) and middle tier (MT) is proposed to achieve the tradeoff between channel capacity and energy consumption. In particular, we firstly devise two pricing factors by considering stability of local spectrum sensing and spectrum sensing quality for SSNs. By the aid of pricing factors, the utility function of this power control problem is formulated by jointly taking into account the revenue of power reduction and the cost of energy consumption for IT or MT SSN. By bearing in mind the utility function maximization and linear differential equation constraint of energy consumption, we further formulate the power control problem as a differential game model under a cooperation or noncooperation scenario, and rigorously obtain the optimal solutions to this game model by employing dynamic programming. Then the congestion mitigation for bottlenecked SUs is derived by alleviating the buffer load over their internal buffers. Simulation results are presented to show the effectiveness of the proposed approach under the rectangular grid based SN-CRN scenario. PMID:28914803

Riparian Sediment Delivery Ratio: Stiff Diagrams and Artifical Neural Networks

EPA Science Inventory

Various methods are used to estimate sediment transport through riparian buffers and grass jilters with the sediment delivery ratio having been the most widely applied. The U.S. Forest Service developed a sediment delivery ratio using the stiff diagram and a logistic curve to int...

Fabrication of hybrid crosslinked network with buffering capabilities and autonomous strengthening characteristics for dental adhesives.

PubMed

Song, Linyong; Ye, Qiang; Ge, Xueping; Misra, Anil; Tamerler, Candan; Spencer, Paulette

2018-02-01

Ingress of bacteria and fluids at the interfacial gaps between the restorative composite biomaterial and the tooth structure contribute to recurrent decay and failure of the composite restoration. The inability of the material to increase the pH at the composite/tooth interface facilitates the outgrowth of bacteria. Neutralizing the microenvironment at the tooth/composite interface offers promise for reducing the damage provoked by cariogenic and aciduric bacteria. We address this problem by designing a dental adhesive composed of hybrid network to provide buffering and autonomous strengthening simultaneously. Two amino functional silanes, 2-hydroxy-3-morpholinopropyl (3-(triethoxysilyl)propyl) carbamate and 2-hydroxy-3-morpholinopropyl (3-(trimethoxysilyl)propyl) carbamate were synthesized and used as co-monomers. Combining free radical initiated polymerization (polymethacrylate-based network) and photoacid-induced sol-gel reaction (polysiloxane) results in the hybrid network formation. Resulting formulations were characterized with regard to real-time photo-polymerization, water sorption, leached species, neutralization, and mechanical properties. Results from real-time FTIR spectroscopic studies indicated that ethoxy was less reactive than methoxy substituent. The neutralization results demonstrated that the methoxy-containing adhesives have acute and delayed buffering capabilities. The mechanical properties of synthetic copolymers tested in dry conditions were improved via condensation reaction of the hydrolyzed organosilanes. The leaching from methoxy containing copolymers was significantly reduced. The sol-gel reaction provided a chronic and persistent reaction in wet condition-performance that offers potential for reducing secondary decay and increasing the functional lifetime of dental adhesives. The interfacial gaps between the restorative composite biomaterial and the tooth structure contributes to recurrent decay and failure of the composite restoration. The inability of the material to increase the pH at the composite/tooth interface facilitates the outgrowth of more cariogenic and aciduric bacteria. This paper reports a novel, synthetic resin that provides buffering capability and autonomous strengthening characteristics. In this work, two amino functional silanes were synthesized and the effect of alkoxy substitutions on the photoacid-induced sol-gel reaction was investigated. We evaluated the neutralization capability (monitoring the pH of lactic acid solution) and the autonomous strengthening property (monitoring the mechanical properties of the hybrid copolymers under wet conditions and quantitatively analyzing the leachable species by HPLC). The novel resin investigated in this study offers the potential benefits of reducing the risk of recurrent decay and prolonging the functional lifetime of dental adhesives. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Use of End-to-End Multicast Measurements for Characterizing Internal Network Behavior

DTIC Science & Technology

2002-08-01

dropping on the basis Random Early Detection ( RED ) [17] is another mechanism by which packet loss may become decorrelated. It remains to be seen whether...this mechanism will be widely deployed in communications networks. On the other hand, the use of RED to merely mark packets will not break correlations...Tail and Random Early Detection ( RED ) buffer discard methods, [17]. We compared the inferred loss and delay with actual probe loss and delay. We found

Netest: A Tool to Measure the Maximum Burst Size, Available Bandwidth and Achievable Throughput

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Guojun; Tierney, Brian

2003-01-31

Distinguishing available bandwidth and achievable throughput is essential for improving network applications' performance. Achievable throughput is the throughput considering a number of factors such as network protocol, host speed, network path, and TCP buffer space, where as available bandwidth only considers the network path. Without understanding this difference, trying to improve network applications' performance is like ''blind men feeling the elephant'' [4]. In this paper, we define and distinguish bandwidth and throughput, and debate which part of each is achievable and which is available. Also, we introduce and discuss a new concept - Maximum Burst Size that is crucial tomore » the network performance and bandwidth sharing. A tool, netest, is introduced to help users to determine the available bandwidth, and provides information to achieve better throughput with fairness of sharing the available bandwidth, thus reducing misuse of the network.« less

Depression and Chronic Health Conditions Among Latinos: The Role of Social Networks.

PubMed

Soto, Sandra; Arredondo, Elva M; Villodas, Miguel T; Elder, John P; Quintanar, Elena; Madanat, Hala

2016-12-01

The purpose of this study was to examine the "buffering hypothesis" of social network characteristics in the association between chronic conditions and depression among Latinos. Cross-sectional self-report data from the San Diego Prevention Research Center's community survey of Latinos were used (n = 393). Separate multiple logistic regression models tested the role of chronic conditions and social network characteristics in the likelihood of moderate-to-severe depressive symptoms. Having a greater proportion of the network comprised of friends increased the likelihood of depression among those with high cholesterol. Having a greater proportion of women in the social network was directly related to the increased likelihood of depression, regardless of the presence of chronic health conditions. Findings suggest that network characteristics may play a role in the link between chronic conditions and depression among Latinos. Future research should explore strategies targeting the social networks of Latinos to improve health outcomes.

pH-Dependent stability of azithromycin in aqueous solution and structure identification of two new degradation products.

PubMed

Saita, Maria Grazia; Aleo, Danilo; Melilli, Barbara; Mangiafico, Sergio; Cro, Melina; Sanfilippo, Claudia; Patti, Angela

2018-05-28

The degradation profile of azithromycin in buffered solutions was investigated using HPLC and found to be pH dependent in the range of 6.0-7.2. Desosaminylazitromycin, derived from hydrolytic loss of cladinose of the parent molecule, was the major degradation product at pH 6.0 but its amount progressively decreased moving toward pH 7.2. Two additional unreported degradation products were also observed and their structures were fully elucidated by MS- and NMR-spectroscopy to be associated with opening of the macrocyclic lactone ring. Copyright © 2018. Published by Elsevier B.V.

3β,5α,6β-Trihy­droxy­androstan-17-one

PubMed Central

Andrade, L.C.R.; de Almeida, M.J.B.M.; Paixão, J.A.; Carvalho, J.F.S.; Sá e Melo, M.L.

2011-01-01

The title compound, C19H30O4, is an androstan-17-one derivative synthesized from the dehydro­epiandrosterone through a sequential addition of an oxidant, followed by a trans-diaxial opening of the epoxide generated, with Bi(OTf)3 (OTf is trifluoro­methane­sulfonate). The six-membered rings have a slightly flattened chair conformation, while the five-membered ring adopts a 14-α envelope conformation. All rings are trans fused. In the crystal, the mol­ecules are connected by O—H⋯O hydrogen bonds involving the hydroxyl and carbonyl groups, forming a three-dimensional network. A quantum mechanical ab initio Roothan Hartree–Fock calculation of the free mol­ecule gives bond lengths, valency angles and ring torsion angles of the free molecule at equilibrium geometry (energy minimum) close to the experimental values. PMID:21754383

4-Nitro­benzyl 2-bromo­acetate

PubMed Central

Zhu, Kai; Liu, Hui; Wang, Yan-Hua; Han, Ping-Fang; Wei, Ping

2009-01-01

In the mol­ecule of the title compound, C9H8BrNO4, the acetate group is close to planar [maximum deviation = 0.042 (3) Å] and is oriented at a dihedral angle of 73.24 (3)° with respect to the aromatic ring. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into a three-dimensional network, forming R 2 2(10) ring motifs. PMID:21582813

N-(1H-Indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-10-26

In the title compound, C14H13N3O3S, the fused ring system is almost planar, the largest deviation from the mean plane being 0.023 (2) Å, and makes a dihedral angle of 47.92 (10)° with the benzene ring of the benzene-sulfonamide moiety. In the crystal, mol-ecules are connected through N-H⋯O hydrogen bonds and weak C-H⋯O contacts, forming a two-dimensional network which is parallel to (010).

N-(3-Chloro-1H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-10-12

In the title compound, C14H12ClN3O3S, the fused five- and six-membered rings are folded slightly along the common edge, forming a dihedral angle of 3.2 (1)°. The mean plane through the indazole system makes a dihedral angle of 30.75 (7)° with the distant benzene ring. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules, forming a two-dimensional network parallel to (001).

3-(2,4-Dichloro­anilino)iso­benzo­furan-1(3H)-one1

PubMed Central

Odabaşoğlu, Mustafa; Büyükgüngör, Orhan

2008-01-01

In the mol­ecule of the title compound, C14H9Cl2NO2, the essentially planar phthalide group is oriented at a dihedral angle of 63.23 (5)° with respect to the substituted aromatic ring. In the crystal structure, inter­molecular C—H⋯O and N—H⋯O hydrogen bonds link the mol­ecules, generating R 4 4(21) ring motifs to form a three-dimensional network. PMID:21202144

A simulation analysis to characterize the dynamics of vaccinating behaviour on contact networks.

PubMed

Perisic, Ana; Bauch, Chris T

2009-05-28

Human behavior influences infectious disease transmission, and numerous "prevalence-behavior" models have analyzed this interplay. These previous analyses assumed homogeneously mixing populations without spatial or social structure. However, spatial and social heterogeneity are known to significantly impact transmission dynamics and are particularly relevant for certain diseases. Previous work has demonstrated that social contact structure can change the individual incentive to vaccinate, thus enabling eradication of a disease under a voluntary vaccination policy when the corresponding homogeneous mixing model predicts that eradication is impossible due to free rider effects. Here, we extend this work and characterize the range of possible behavior-prevalence dynamics on a network. We simulate transmission of a vaccine-preventable infection through a random, static contact network. Individuals choose whether or not to vaccinate on any given day according to perceived risks of vaccination and infection. We find three possible outcomes for behavior-prevalence dynamics on this type of network: small final number vaccinated and final epidemic size (due to rapid control through voluntary ring vaccination); large final number vaccinated and significant final epidemic size (due to imperfect voluntary ring vaccination), and little or no vaccination and large final epidemic size (corresponding to little or no voluntary ring vaccination). We also show that the social contact structure enables eradication under a broad range of assumptions, except when vaccine risk is sufficiently high, the disease risk is sufficiently low, or individuals vaccinate too late for the vaccine to be effective. For populations where infection can spread only through social contact network, relatively small differences in parameter values relating to perceived risk or vaccination behavior at the individual level can translate into large differences in population-level outcomes such as final size and final number vaccinated. The qualitative outcome of rational, self interested behaviour under a voluntary vaccination policy can vary substantially depending on interactions between social contact structure, perceived vaccine and disease risks, and the way that individual vaccination decision-making is modelled.

A simulation analysis to characterize the dynamics of vaccinating behaviour on contact networks

PubMed Central

2009-01-01

Background Human behavior influences infectious disease transmission, and numerous "prevalence-behavior" models have analyzed this interplay. These previous analyses assumed homogeneously mixing populations without spatial or social structure. However, spatial and social heterogeneity are known to significantly impact transmission dynamics and are particularly relevant for certain diseases. Previous work has demonstrated that social contact structure can change the individual incentive to vaccinate, thus enabling eradication of a disease under a voluntary vaccination policy when the corresponding homogeneous mixing model predicts that eradication is impossible due to free rider effects. Here, we extend this work and characterize the range of possible behavior-prevalence dynamics on a network. Methods We simulate transmission of a vaccine-prevetable infection through a random, static contact network. Individuals choose whether or not to vaccinate on any given day according to perceived risks of vaccination and infection. Results We find three possible outcomes for behavior-prevalence dynamics on this type of network: small final number vaccinated and final epidemic size (due to rapid control through voluntary ring vaccination); large final number vaccinated and significant final epidemic size (due to imperfect voluntary ring vaccination), and little or no vaccination and large final epidemic size (corresponding to little or no voluntary ring vaccination). We also show that the social contact structure enables eradication under a broad range of assumptions, except when vaccine risk is sufficiently high, the disease risk is sufficiently low, or individuals vaccinate too late for the vaccine to be effective. Conclusion For populations where infection can spread only through social contact network, relatively small differences in parameter values relating to perceived risk or vaccination behavior at the individual level can translate into large differences in population-level outcomes such as final size and final number vaccinated. The qualitative outcome of rational, self interested behaviour under a voluntary vaccination policy can vary substantially depending on interactions between social contact structure, perceived vaccine and disease risks, and the way that individual vaccination decision-making is modelled. PMID:19476616

Experimental observation of motion of edge dislocations in Ge/Ge{sub x}Si{sub 1–x}/Si(001) (x = 0.2–0.6) heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolkhovityanov, Yu. B., E-mail: bolkhov@isp.nsc.ru; Gutakovskii, A. K.; Deryabin, A. S.

2016-11-15

The Ge/Ge{sub x}Si{sub 1–x}/Si(001) (x = 0.2–0.6) heterostructures grown by the molecular epitaxy method are analyzed using high-resolution electron microscopy with atomic resolution. The thickness of the Ge{sub x}Si{sub 1–x} buffer layer is 7–35 nm. It is shown that such heterostructures relax in two stages: an ordered network of edge dislocations is formed during their growth (500°C) at the Ge/GeSi interface and then, contrary to the generally accepted opinion concerning their immobility, some of the edge dislocations move through the buffer GeSi layer to the GeSi/Si(001) interface during annealing at higher temperatures and x > 0.3. It is found thatmore » plastic relaxation of the GeSi buffer layer occurs due to motion of dislocation complexes of the edge type, consisting of a pair of complementary 60° dislocations with the ends of (111) extra planes located approximately at a distance from 2 to 12 interplanar spacings. It is shown that the penetration of dislocation complexes into the GeSi buffer layer and further to the GeSi/Si interface is intensified with increasing annealing temperature (600–800°C) and the fraction of Ge in the buffer layer.« less

Synthesis, pharmacology, crystal properties, and quantitative solvation studies from a drug transport perspective for three new 1,2,4-thiadiazoles.

PubMed

Perlovich, German L; Volkova, Tatyana V; Proshin, Alexey N; Sergeev, Dmitriy Yu; Bui, Cong Trinh; Petrova, Ludmila N; Bachurin, Sergey O

2010-09-01

A novel 1,2,4-thiadiazoles were synthesized. Crystal structures of these compounds were solved by X-ray diffraction experiments and comparative analysis of molecular conformational states, packing architecture, and hydrogen bonds networks were carried out. Thermodynamic aspects of sublimation processes of studied compounds were determined using temperature dependencies of vapor pressure. Thermophysical characteristics of the molecular crystals were obtained and compared with the sublimation and structural parameters. Solubility and solvation processes of 1,2,4-thiadiazoles in buffer, n-hexane and n-octanol were studied within the wide range of temperature intervals and thermodynamic functions were calculated. Specific and nonspecific interactions of molecules resolved in crystals and solvents were estimated and compared. Distribution processes of compounds in buffer/n-octanol and buffer/n-hexane systems (describing different types of membranes) were investigated. Analysis of transfer processes of studied molecules from the buffer to n-octanol/n-hexane phases was carried out by the diagram method with evaluation of the enthalpic and entropic terms. This approach allows us to design drug molecules with optimal passive transport properties. Calcium-blocking properties of the substances were evaluated.

Rines/RNF180, a novel RING finger gene-encoded product, is a membrane-bound ubiquitin ligase.

PubMed

Ogawa, Miyuki; Mizugishi, Kiyomi; Ishiguro, Akira; Koyabu, Yoshio; Imai, Yuzuru; Takahashi, Ryosuke; Mikoshiba, Katsuhiko; Aruga, Jun

2008-04-01

We identified and characterized a novel RING finger gene, Rines/RNF180, which is well conserved among vertebrates. Putative Rines gene product (Rines) contains a RING finger domain, a basic coiled-coil domain, a novel conserved domain (DSPRC) and a C-terminal hydrophobic region that is predicted to be a transmembrane domain. N-terminally epitope tagged-Rines (Nt-Rines) was detected in the endoplasmic reticulum membrane/nuclear envelope in cultured mammalian cells. Nt-Rines was not extracted by high salt or alkaline buffers and was degraded in intact endoplasmic reticulum treated with proteinase K, indicating that Nt-Rines is an integral membrane protein with most of its N-terminal regions in the cytoplasm. Rines was expressed in brain, kidney, testis and uterus of adult mice, and in developing lens and brain, particularly in the ventricular layer of the cerebral cortex at embryonic stages. In cultured cells, Nt-Rines can bind another protein and promoted its degradation. The degradation was inhibited by proteasomal inhibitors. In addition, Nt-Rines itself was heavily ubiquitinated and degraded by proteasome. The involvement of Rines in the ubiquitin-proteasome pathway was further supported by its binding to the UbcH6 ubiquitin-conjugating enzyme and by its trans-ubiquitination enhancing activities. These results suggest that Rines is a membrane-bound E3 ubiquitin ligase.

Small worlds in space: Synchronization, spatial and relational modularity

NASA Astrophysics Data System (ADS)

Brede, M.

2010-06-01

In this letter we investigate networks that have been optimized to realize a trade-off between enhanced synchronization and cost of wire to connect the nodes in space. Analyzing the evolved arrangement of nodes in space and their corresponding network topology, a class of small-world networks characterized by spatial and network modularity is found. More precisely, for low cost of wire optimal configurations are characterized by a division of nodes into two spatial groups with maximum distance from each other, whereas network modularity is low. For high cost of wire, the nodes organize into several distinct groups in space that correspond to network modules connected on a ring. In between, spatially and relationally modular small-world networks are found.

Turing instability in reaction-diffusion models on complex networks

NASA Astrophysics Data System (ADS)

Ide, Yusuke; Izuhara, Hirofumi; Machida, Takuya

2016-09-01

In this paper, the Turing instability in reaction-diffusion models defined on complex networks is studied. Here, we focus on three types of models which generate complex networks, i.e. the Erdős-Rényi, the Watts-Strogatz, and the threshold network models. From analysis of the Laplacian matrices of graphs generated by these models, we numerically reveal that stable and unstable regions of a homogeneous steady state on the parameter space of two diffusion coefficients completely differ, depending on the network architecture. In addition, we theoretically discuss the stable and unstable regions in the cases of regular enhanced ring lattices which include regular circles, and networks generated by the threshold network model when the number of vertices is large enough.

Estimating the off-network presence of STAA dimensioned vehicles on North Carolina roadways using CMV crash data, 2001-2005

DOT National Transportation Integrated Search

2008-05-06

The present study used commercial motor vehicle (CMV) crash data from NCDOTs Traffic Engineering Accident : Analysis System (TEAAS) to infer the presence and relative extent of STAA dimensioned vehicles operating : beyond the 3-mile buffer of the ...

Efficient Buffering Scheme in the LMA for Seamless Handover in PMIPv6

NASA Astrophysics Data System (ADS)

Kim, Kwang-Ryoul; Lee, Hyo-Beom; Choi, Hyon-Young; Min, Sung-Gi; Han, Youn-Hee

Proxy Mobile IPv6 (PMIPv6) is proposed as a new network-based local mobility protocol which does not involve the Mobile Node (MN) in mobility management. PMIPv6, which uses link-layer attachment information, reduces the movement detection time and eliminates duplicate address detection procedures in order to provide faster handover than Mobile IPv6 (MIPv6). To eliminate packet loss during the handover period, the Local Mobility Anchor (LMA) buffering scheme is proposed. In this scheme, the LMA buffers lost packets of the Mobile Access Gateway (MAG) and the MN during the handover and recovers them after handover. A new Automatic Repeat reQuest (ARQ) handler is defined which efficiently manages the LMA buffer. The ARQ handler relays ARQ result between the MAG and the MN to the LMA. The LMA removes any buffered packets which have been successfully delivered to the MN. The ARQ handler recovers the packet loss during the handover using buffered packets in the LMA. The ARQ information, between the MAG and LMA, is inserted in the outer header of IP-in-IP encapsulated packets of a standard PMIPv6 tunnel. Since the proposed scheme simply adds information to the standard operation of an IP-in-IP tunnel between the LMA and the MAG, it can be implemented seamlessly without modification to the original PMIPv6 messages and signaling sequence. Unlike other Fast Handovers for Mobile IPv6 (FMIPv6) based enhancement for PMIPv6, the proposed scheme does not require any handover related information before the actual handover.

Pass-transistor very large scale integration

NASA Technical Reports Server (NTRS)

Maki, Gary K. (Inventor); Bhatia, Prakash R. (Inventor)

2004-01-01

Logic elements are provided that permit reductions in layout size and avoidance of hazards. Such logic elements may be included in libraries of logic cells. A logical function to be implemented by the logic element is decomposed about logical variables to identify factors corresponding to combinations of the logical variables and their complements. A pass transistor network is provided for implementing the pass network function in accordance with this decomposition. The pass transistor network includes ordered arrangements of pass transistors that correspond to the combinations of variables and complements resulting from the logical decomposition. The logic elements may act as selection circuits and be integrated with memory and buffer elements.

Ultrastructural investigations for reducing endothelial cell damage of vein grafts during CABG-operation and practical consequences.

PubMed

Hickethier, T; Dämmrich, J; Silber, R E; Finster, S; Elert, O

1999-02-01

In the present study the influence of different storage solutions on endothelial integrity or damage was investigated with direct methods particularly with transmission electron microscopy (TEM), scanning electron microscopy (SEM) and immunohistochemistry. Saphenous vein segments of 10 cm in length were taken surgically from 6 male CABG-patients (aged 60-70) under standardized conditions. Each vein segment was cut into rings, which were incubated at room temperature for 45 minutes in different storage solutions, particularly in 0.9% sodium chloride solution and in buffered solution (M 199) with 5% human serum albumin respectively. Then, the vein segments were fixed in 3.5% glutaraldehyde and prepared for scanning and transmission electron microscopy to evaluate the endothelial damage. In addition, immunohistochemical staining (CD34, PECAM and Factor VIII) was performed. When using 0.9% sodium chloride solution, the SEM-examination revealed that 55% of the cell population was destroyed. In comparison to these findings only 26% of the endothelial cell population was damaged when the venous segment was stored in buffered solution with 5% albumin (p<0.01). In immunohistochemistry (CD34, PECAM, Factor VIII) these findings were supported. This study demonstrates the importance of storage solutions in regard to endothelial integrity. For best preservation of endothelium it is necessary to modify conventional storage methods. So, storage in buffered solution with albumin has shown much better endothelial cell preservation compared with physiological saline which might reduce the obliteration rate of CABG in future.

Analgesic effect of Facebook: Priming with online social networking may boost felt relatedness that buffers against physical pain.

PubMed

Ho, Liang-Chu; Wu, Wen-Hsiung; Chiou, Wen-Bin

2016-10-01

Social networking sites (SNSs) are extremely popular for providing users with a convenient platform for acquiring social connections and thereby feeling relatedness. Plenty of literature has shown that mental representations of social support can reduce the perception of physical pain. The current study tested whether thinking about SNS would interfere with users' perceptions of experimentally induced pain. Ninety-six undergraduate Facebook users were recruited to participate in a priming-based experiment. They were randomly assigned to one of the three study conditions (SNS prime, neutral prime, or no prime) via rating the aesthetics of logos. The results showed that participants exposed to SNS primes reported less pain of immersion in hot water than did both control groups (neutral- and no-prime). Felt relatedness mediated the link between SNS primes and diminished pain perceptions. This research provides the first demonstration that thinking about SNS can lower experienced physical pain among Facebook users. Online social networking may serve as an analgesic buffer against pain experience than previously thought. The SNS-enabled analgesia has far reaching implications for pain relief applications and the enhancement of well-being in human-interaction techniques. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

The Quasar Network Observations in e-VLBI Mode

NASA Astrophysics Data System (ADS)

Bezrukov, I.; Finkelstein, A.; Ipatov, A.; Kaidanovsky, A.; Mikhailov, A.; Salnikov, A.; Yakovlev, V.

2011-07-01

This paper describes activity of the Institute of Applied Astronomy in developing real-time VLBI-system using high speed digital communication links. Real-time VLBI-technology has been developing at IAA since 2007 when the very first experiment was successfully done with Haystack observatory. All observatories of VLBI-Network Quasar were connected by "last mile" communication channels and via the Internet at 100 Mbps rate. Additional UNIX servers were installed for data buffering. Now e-VLBI sessions are carried out routinely within domestic VLBI-programs for UT1-determination. Observational data of 1-hour sessions are transmitted simultaneously from Svetloe, Zelenchukskaya and Badary observatories to the IAA Data Processing Center in Saint-Petersburg through fiber lines at 50-70 Mbps via Tsunami-UDP protocol. In September 2010 few scans were successfully transmitted from Quasar-Network observatories to Correlator Center at Shanghai observatory and vice-versa from Shanghai observatory to Correlator of RAS. Within these experiments observation data recorded by Mark 5B recorder are transmitted to the buffer server during time interval when an antenna pointed from one source to another. This procedure allows us to reduce total time of obtaining final result by 30%. Now an advanced algorithm for automation of the data transmitting process from the recorder to correlator is developing.

Trauma-Exposed Latina Immigrants’ Networks: A Social Network Analysis Approach

PubMed Central

Hurtado-de-Mendoza, Alejandra; Serrano, Adriana; Gonzales, Felisa A.; Fernandez, Nicole C.; Cabling, Mark; Kaltman, Stacey

2015-01-01

Objective Trauma exposure among Latina immigrants is common. Social support networks can buffer the impact of trauma on mental health. This study characterizes the social networks of trauma-exposed Latina immigrants using a social network analysis perspective. Methods In 2011–2012 a convenience sample (n=28) of Latina immigrants with trauma exposure and presumptive depression or posttraumatic stress disorder was recruited from a community clinic in Washington DC. Participants completed a social network assessment and listed up to ten persons in their network (alters). E-Net was used to describe the aggregate structural, interactional, and functional characteristics of networks and Node-XL was used in a case study to diagram one network. Results Most participants listed children (93%), siblings (82%), and friends (71%) as alters, and most alters lived in the US (69%). Perceived emotional support and positive social interaction were higher compared to tangible, language, information, and financial support. A case study illustrates the use of network visualizations to assess the strengths and weaknesses of social networks. Conclusions Targeted social network interventions to enhance supportive networks among trauma-exposed Latina immigrants are warranted. PMID:28078194

Trauma-Exposed Latina Immigrants' Networks: A Social Network Analysis Approach.

PubMed

Hurtado-de-Mendoza, Alejandra; Serrano, Adriana; Gonzales, Felisa A; Fernandez, Nicole C; Cabling, Mark; Kaltman, Stacey

2016-11-01

Trauma exposure among Latina immigrants is common. Social support networks can buffer the impact of trauma on mental health. This study characterizes the social networks of trauma-exposed Latina immigrants using a social network analysis perspective. In 2011-2012 a convenience sample (n=28) of Latina immigrants with trauma exposure and presumptive depression or posttraumatic stress disorder was recruited from a community clinic in Washington DC. Participants completed a social network assessment and listed up to ten persons in their network (alters). E-Net was used to describe the aggregate structural, interactional, and functional characteristics of networks and Node-XL was used in a case study to diagram one network. Most participants listed children (93%), siblings (82%), and friends (71%) as alters, and most alters lived in the US (69%). Perceived emotional support and positive social interaction were higher compared to tangible, language, information, and financial support. A case study illustrates the use of network visualizations to assess the strengths and weaknesses of social networks. Targeted social network interventions to enhance supportive networks among trauma-exposed Latina immigrants are warranted.

A framework for visualization of battlefield network behavior

NASA Astrophysics Data System (ADS)

Perzov, Yury; Yurcik, William

2006-05-01

An extensible network simulation application was developed to study wireless battlefield communications. The application monitors node mobility and depicts broadcast and unicast traffic as expanding rings and directed links. The network simulation was specially designed to support fault injection to show the impact of air strikes on disabling nodes. The application takes standard ns-2 trace files as an input and provides for performance data output in different graphical forms (histograms and x/y plots). Network visualization via animation of simulation output can be saved in AVI format that may serve as a basis for a real-time battlefield awareness system.

Architectural impact of FDDI network on scheduling hard real-time traffic

NASA Technical Reports Server (NTRS)

Agrawal, Gopal; Chen, Baio; Zhao, Wei; Davari, Sadegh

1991-01-01

The architectural impact on guaranteeing synchronous message deadlines in FDDI (Fiber Distributed Data Interface) token ring networks is examined. The FDDI network does not have facility to support (global) priority arbitration which is a useful facility for scheduling hard real time activities. As a result, it was found that the worst case utilization of synchronous traffic in an FDDI network can be far less than that in a centralized single processor system. Nevertheless, it is proposed and analyzed that a scheduling method can guarantee deadlines of synchronous messages having traffic utilization up to 33 pct., the highest to date.

Three-dimensional {Co(3+)-Zn2+} and {Co(3+)-Cd2+} networks originated from carboxylate-rich building blocks: syntheses, structures, and heterogeneous catalysis.

PubMed

Kumar, Girijesh; Gupta, Rajeev

2013-10-07

The present work shows the utilization of Co(3+) complexes appended with either para- or meta-arylcarboxylic acid groups as the molecular building blocks for the construction of three-dimensional {Co(3+)-Zn(2+)} and {Co(3+)-Cd(2+)} heterobimetallic networks. The structural characterizations of these networks show several interesting features including well-defined pores and channels. These networks function as heterogeneous and reusable catalysts for the regio- and stereoselective ring-opening reactions of various epoxides and size-selective cyanation reactions of assorted aldehydes.

Extended write combining using a write continuation hint flag

DOEpatents

Chen, Dong; Gara, Alan; Heidelberger, Philip; Ohmacht, Martin; Vranas, Pavlos

2013-06-04

A computing apparatus for reducing the amount of processing in a network computing system which includes a network system device of a receiving node for receiving electronic messages comprising data. The electronic messages are transmitted from a sending node. The network system device determines when more data of a specific electronic message is being transmitted. A memory device stores the electronic message data and communicating with the network system device. A memory subsystem communicates with the memory device. The memory subsystem stores a portion of the electronic message when more data of the specific message will be received, and the buffer combines the portion with later received data and moves the data to the memory device for accessible storage.

Traffic routing for multicomputer networks with virtual cut-through capability

NASA Technical Reports Server (NTRS)

Kandlur, Dilip D.; Shin, Kang G.

1992-01-01

Consideration is given to the problem of selecting routes for interprocess communication in a network with virtual cut-through capability, while balancing the network load and minimizing the number of times that a message gets buffered. An approach is proposed that formulates the route selection problem as a minimization problem with a link cost function that depends upon the traffic through the link. The form of this cost function is derived using the probability of establishing a virtual cut-through route. The route selection problem is shown to be NP-hard, and an algorithm is developed to incrementally reduce the cost by rerouting the traffic. The performance of this algorithm is exemplified by two network topologies: the hypercube and the C-wrapped hexagonal mesh.

Uranium(III)-carbon multiple bonding supported by arene δ-bonding in mixed-valence hexauranium nanometre-scale rings.

PubMed

Wooles, Ashley J; Mills, David P; Tuna, Floriana; McInnes, Eric J L; Law, Gareth T W; Fuller, Adam J; Kremer, Felipe; Ridgway, Mark; Lewis, William; Gagliardi, Laura; Vlaisavljevich, Bess; Liddle, Stephen T

2018-05-29

Despite the fact that non-aqueous uranium chemistry is over 60 years old, most polarised-covalent uranium-element multiple bonds involve formal uranium oxidation states IV, V, and VI. The paucity of uranium(III) congeners is because, in common with metal-ligand multiple bonding generally, such linkages involve strongly donating, charge-loaded ligands that bind best to electron-poor metals and inherently promote disproportionation of uranium(III). Here, we report the synthesis of hexauranium-methanediide nanometre-scale rings. Combined experimental and computational studies suggest overall the presence of formal uranium(III) and (IV) ions, though electron delocalisation in this Kramers system cannot be definitively ruled out, and the resulting polarised-covalent U = C bonds are supported by iodide and δ-bonded arene bridges. The arenes provide reservoirs that accommodate charge, thus avoiding inter-electronic repulsion that would destabilise these low oxidation state metal-ligand multiple bonds. Using arenes as electronic buffers could constitute a general synthetic strategy by which to stabilise otherwise inherently unstable metal-ligand linkages.

Nucleophilic substitution at centers other than carbon: reaction at the chlorine of N-chloroacetanilides with triethylamine as the nucleophile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Underwood, G.R.; Dietze, P.E.

1984-12-28

The reaction between triethylamine (TEA) and a series of para-substituted N-chloroacetanilides has been studied in aqueous solution buffered to pHs between 1 and 5. The exclusive product derived from the aromatic moiety is the corresponding acetanilide. The reaction occurs via two parallel pseudo-second-order paths, one acid catalyzed (the Orton-like mechanism), the other uncatalyzed. The uncatalyzed reaction is accelerated by the presence of electron-withdrawing substituents on the aromatic ring and can best be represented as nucleophilic displacement at chlorine. It therefore appears to be the prototype of a convenient class of reactions for the study of displacement reactions at chlorine. Themore » rho value for this reaction is 3.87, indicating substantial negative charge buildup in the aromatic ring during of the transition state. The acid-catalyzed reaction is more complex, presumable involving a protonation equilibrium for the N-chloroacetanilide prior to the rate-determining step similar to that in the Orton reaction. 15 references, 2 figures, 3 tables.« less

Long-term drought sensitivity of trees in second-growth forests in a humid region

Treesearch

Neil Pederson; Kacie Tackett; Ryan W. McEwan; Stacy Clark; Adrienne Cooper; Glade Brosi; Ray Eaton; R. Drew Stockwell

2012-01-01

Classical field methods of reconstructing drought using tree rings in humid, temperate regions typically target old trees from drought-prone sites. This approach limits investigators to a handful of species and excludes large amounts of data that might be useful, especially for coverage gaps in large-scale networks. By sampling in more “typical” forests, network...

CSMA/RN: A universal protocol for gigabit networks

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, Kurt J.; Overstreet, C. Michael; Khanna, S.; Paterra, Frank

1990-01-01

Networks must provide intelligent access for nodes to share the communications resources. In the range of 100 Mbps to 1 Gbps, the demand access class of protocols were studied extensively. Many use some form of slot or reservation system and many the concept of attempt and defer to determine the presence or absence of incoming information. The random access class of protocols like shared channel systems (Ethernet), also use the concept of attempt and defer in the form of carrier sensing to alleviate the damaging effects of collisions. In CSMA/CD, the sensing of interference is on a global basis. All systems discussed above have one aspect in common, they examine activity on the network either locally or globally and react in an attempt and whatever mechanism. Of the attempt + mechanisms discussed, one is obviously missing; that is attempt and truncate. Attempt and truncate was studied in a ring configuration called the Carrier Sensed Multiple Access Ring Network (CSMA/RN). The system features of CSMA/RN are described including a discussion of the node operations for inserting and removing messages and for handling integrated traffic. The performance and operational features based on analytical and simulation studies which indicate that CSMA/RN is a useful and adaptable protocol over a wide range of network conditions are discussed. Finally, the research and development activities necessary to demonstrate and realize the potential of CSMA/RN as a universal, gigabit network protocol is outlined.

Pharmacological study of the mechanisms involved in the vasodilator effect produced by the acute application of triiodothyronine to rat aortic rings

PubMed Central

Lozano-Cuenca, J.; López-Canales, O.A.; Aguilar-Carrasco, J.C.; Villagrana-Zesati, J.R.; López-Mayorga, R.M.; Castillo-Henkel, E.F.; López-Canales, J.S.

2016-01-01

A relationship between thyroid hormones and the cardiovascular system has been well established in the literature. The present in vitro study aimed to investigate the mechanisms involved in the vasodilator effect produced by the acute application of 10-8–10-4 M triiodothyronine (T3) to isolated rat aortic rings. Thoracic aortic rings from 80 adult male Wistar rats were isolated and mounted in tissue chambers filled with Krebs-Henseleit bicarbonate buffer in order to analyze the influence of endothelial tissue, inhibitors and blockers on the vascular effect produced by T3. T3 induced a vasorelaxant response in phenylephrine-precontracted rat aortic rings at higher concentrations (10-4.5–10-4.0 M). This outcome was unaffected by 3.1×10-7 M glibenclamide, 10-3 M 4-aminopyridine (4-AP), 10-5 M indomethacin, or 10-5 M cycloheximide. Contrarily, vasorelaxant responses to T3 were significantly (P<0.05) attenuated by endothelium removal or the application of 10-6 M atropine, 10-5 M L-NG-nitroarginine methyl ester (L-NAME), 10-7 M 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10-6 M (9S,10R,12R)-2,3,9,10,11,12-Hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3′,2′,1′-kl]pyrrolo[3,4-i](1,6)benzodiazocine-10-carboxylic acid, methyl ester KT 5823, 10-2 M tetraethylammonium (TEA), or 10-7 M apamin plus 10-7 M charybdotoxin. The results suggest the involvement of endothelial mechanisms in the vasodilator effect produced by the acute in vitro application of T3 to rat aortic rings. Possible mechanisms include the stimulation of muscarinic receptors, activation of the NO-cGMP-PKG pathway, and opening of Ca2+-activated K+ channels. PMID:27464023

1,5-Bis(penta­fluoro­phen­yl)-3-phenyl­pent-2-ene-1,5-dione

PubMed Central

Schwarzer, Anke; Weber, Edwin

2009-01-01

In the title compound, C23H8F10O2, the three arene rings are twisted one with respect to the other: the two perfluorinated arene rings are tilted to each other by an angle of 60.39 (7)°. They are inclined to the non-fluorinated phenyl unit by 38.85 (7) and 78.74 (7)°. The olefinic double bond adopts an E configuration. The carbonyl groups are not in a coplanar alignment with reference to the neighbouring arene rings. The crystal packing features a number of weak C—H⋯F inter­actions, which leads to the formation of a three-dimensional network. PMID:21578393

Behavioral Mapless Navigation Using Rings

NASA Technical Reports Server (NTRS)

Monroe, Randall P.; Miller, Samuel A.; Bradley, Arthur T.

2012-01-01

This paper presents work on the development and implementation of a novel approach to robotic navigation. In this system, map-building and localization for obstacle avoidance are discarded in favor of moment-by-moment behavioral processing of the sonar sensor data. To accomplish this, we developed a network of behaviors that communicate through the passing of rings, data structures that are similar in form to the sonar data itself and express the decisions of each behavior. Through the use of these rings, behaviors can moderate each other, conflicting impulses can be mediated, and designers can easily connect modules to create complex emergent navigational techniques. We discuss the development of a number of these modules and their successful use as a navigation system in the Trinity omnidirectional robot.

New design of a triplexer using ring resonator integrated with directional coupler based on photonic crystals

NASA Astrophysics Data System (ADS)

Wu, Yaw-Dong; Shih, Tien-Tsorng; Lee, Jian-Jang

2009-11-01

In this paper, we proposed the design of directional coupler integrated with ring resonator based on two-dimensional photonic crystals (2D PCs) to develop a triplexer filter. It can be widely used as the fiber access network element for multiplexer-demultiplexer wavelength selective in fiber-to-the-home (FTTH) communication systems. The directional coupler is chosen to separate the wavelengths of 1490nm and 1310nm. The ring resonator separates the wavelength of 1550nm. The transmission efficiency is larger than 90%. Besides, the total size of propose triplexer is only 19μm×12μm. We present simulation results using the finite-difference time-domain (FDTD) method for the proposed structure.

Crystal structure of N-(1-allyl-3-chloro-4-eth-oxy-1H-indazol-5-yl)-4-meth-oxybenzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-09-01

In the title compound, C19H20ClN3O4S, the benzene ring is inclined to the indazole ring system (r.m.s. deviation = 0.014 Å) by 65.07 (8)°. The allyl and eth-oxy groups are almost normal to the indazole ring, as indicated by the respective torsion angles [N-N-C-C = 111.6 (2) and C-C-O-C = -88.1 (2)°]. In the crystal, mol-ecules are connected by N-H⋯N hydrogen bonds, forming helical chains propagating along [010]. The chains are linked by C-H⋯O hydrogen bonds, forming a three-dimensional network.

A comparison of salivary pH in sympatric wild lemurs (Lemur catta and Propithecus verreauxi) at Beza Mahafaly Special Reserve, Madagascar.

PubMed

Cuozzo, Frank P; Sauther, Michelle L; Yamashita, Nayuta; Lawler, Richard R; Brockman, Diane K; Godfrey, Laurie R; Gould, Lisa; Youssouf, Ibrahim Antho Jacky; Lent, Cheryl; Ratsirarson, Joelisoa; Richard, Alison F; Scott, Jessica R; Sussman, Robert W; Villers, Lynne M; Weber, Martha A; Willis, George

2008-04-01

Chemical deterioration of teeth is common among modern humans, and has been suggested for some extinct primates. Dental erosion caused by acidic foods may also obscure microwear signals of mechanical food properties. Ring-tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar, display frequent severe tooth wear and subsequent tooth loss. In contrast, sympatric Verreaux's sifaka display far less tooth wear and infrequent tooth loss, despite both species regularly consuming acidic tamarind fruit. We investigated the potential impact of dietary acidity on tooth wear, collecting data on salivary pH from both species, as well as salivary pH from ring-tailed lemurs at Tsimanampesotse National Park, Madagascar. We also collected salivary pH data from ring-tailed lemurs at the Indianapolis Zoo, none of which had eaten for at least 12 hr before data collection. Mean salivary pH for the BMSR ring-tailed lemurs (8.098, n=41, SD=0.550) was significantly more alkaline than Verreaux's sifaka (7.481, n=26, SD=0.458). The mean salivary pH of BMSR (8.098) and Tsimanampesotse (8.080, n=25, SD=0.746) ring-tailed lemurs did not differ significantly. Salivary pH for the Indianapolis Zoo sample (8.125, n=16, SD=0.289) did not differ significantly from either the BMSR or Tsimanampesotse ring-tailed lemurs, but was significantly more alkaline than the BMSR Verreaux's sifaka sample. Regardless of the time between feeding and collection of pH data (from several minutes to nearly 1 hr), salivary pH for each wild lemur was above the "critical" pH of 5.5, below which enamel demineralization occurs. Thus, the high pH of lemur saliva suggests a strong buffering capacity, indicating the impact of acidic foods on dental wear is short-lived, likely having a limited effect. However, tannins in tamarind fruit may increase friction between teeth, thereby increasing attrition and wear in lemurs. These data also suggest that salivary pH varies between lemur species, corresponding to broad dietary categories.

Network connectivity enhancement by exploiting all optical multicast in semiconductor ring laser

NASA Astrophysics Data System (ADS)

Siraj, M.; Memon, M. I.; Shoaib, M.; Alshebeili, S.

2015-03-01

The use of smart phone and tablet applications will provide the troops for executing, controlling and analyzing sophisticated operations with the commanders providing crucial documents directly to troops wherever and whenever needed. Wireless mesh networks (WMNs) is a cutting edge networking technology which is capable of supporting Joint Tactical radio System (JTRS).WMNs are capable of providing the much needed bandwidth for applications like hand held radios and communication for airborne and ground vehicles. Routing management tasks can be efficiently handled through WMNs through a central command control center. As the spectrum space is congested, cognitive radios are a much welcome technology that will provide much needed bandwidth. They can self-configure themselves, can adapt themselves to the user requirement, provide dynamic spectrum access for minimizing interference and also deliver optimal power output. Sometimes in the indoor environment, there are poor signal issues and reduced coverage. In this paper, a solution utilizing (CR WMNs) over optical network is presented by creating nanocells (PCs) inside the indoor environment. The phenomenon of four-wave mixing (FWM) is exploited to generate all-optical multicast using semiconductor ring laser (SRL). As a result same signal is transmitted at different wavelengths. Every PC is assigned a unique wavelength. By using CR technology in conjunction with PC will not only solve network coverage issue but will provide a good bandwidth to the secondary users.

NARX neural network Prediction of SYMH and ASYH indices for geomagnetic storms of solar cycle 24 including recent St. Patrick's day, 2015 storm

NASA Astrophysics Data System (ADS)

Bhaskar, A. T.; Vichare, G.

2017-12-01

Here, an attempt is made to develop a prediction model for SYMH and ASYH geomagnetic indices using Artificial Neural Network (ANN). SYMH and ASYH indices represent longitudinal symmetric and asymmetric component of the ring current. The ring current state depends on its past conditions therefore, it is necessary to consider its history for prediction. To account this effect Nonlinear Autoregressive Network with eXogenous inputs (NARX) is implemented. This network considers input history of 30 minutes and output feedback of 120 minutes. Solar wind parameters mainly velocity, density and interplanetary magnetic field are used as inputs. SYMH and ASYH indices during geomagnetic storms of 1998-2013, having minimum SYMH <-85 nT are used as the target for training two independent networks. We present the prediction of SYMH and ASYH indices during 9 geomagnetic storms of solar cycle 24 including the recent largest storm occurred on St. Patrick's day, 2015. The present prediction model reproduces the entire time profile of SYMH and ASYH indices along with small variations of 10-30 minutes to good extent within noise level, indicating significant contribution of interplanetary sources and past state of the magnetosphere. However, during the main phase of major storms, residuals (observed-modeled) are found to be large, suggesting influence of internal factors such as magnetospheric processes.

A 16-bit Coherent Ising Machine for One-Dimensional Ring and Cubic Graph Problems

NASA Astrophysics Data System (ADS)

Takata, Kenta; Marandi, Alireza; Hamerly, Ryan; Haribara, Yoshitaka; Maruo, Daiki; Tamate, Shuhei; Sakaguchi, Hiromasa; Utsunomiya, Shoko; Yamamoto, Yoshihisa

2016-09-01

Many tasks in our modern life, such as planning an efficient travel, image processing and optimizing integrated circuit design, are modeled as complex combinatorial optimization problems with binary variables. Such problems can be mapped to finding a ground state of the Ising Hamiltonian, thus various physical systems have been studied to emulate and solve this Ising problem. Recently, networks of mutually injected optical oscillators, called coherent Ising machines, have been developed as promising solvers for the problem, benefiting from programmability, scalability and room temperature operation. Here, we report a 16-bit coherent Ising machine based on a network of time-division-multiplexed femtosecond degenerate optical parametric oscillators. The system experimentally gives more than 99.6% of success rates for one-dimensional Ising ring and nondeterministic polynomial-time (NP) hard instances. The experimental and numerical results indicate that gradual pumping of the network combined with multiple spectral and temporal modes of the femtosecond pulses can improve the computational performance of the Ising machine, offering a new path for tackling larger and more complex instances.

Effect of fatty acids on endothelium-dependent relaxation in the rabbit aorta.

PubMed

Edirisinghe, Indika; McCormick Hallam, Kellie; Kappagoda, C Tissa

2006-08-01

The metabolic syndrome, Type II (non-insulin-dependent) diabetes and obesity are associated with endothelial dysfunction and increased plasma concentrations of NEFAs (non-esterified fatty acids; free fatty acids). The present study was undertaken to define the inhibitory effects of saturated NEFAs on EDR (endothelium-dependent relaxation). Experiments were performed in rings of rabbit aorta to establish (i) dose-response relationships, (ii) the effect of chain length, (iii) the effect of the presence of double bonds, (iv) reversibility and time course of inhibition, and (v) the effect on nitric oxide production. Aortic rings were incubated (1 h) with NEFA-albumin complexes derived from lauric (C(12:0)), myristic (C(14:0)), palmitic (C(16:0)), stearic (C(18:0)) and linolenic (C(18:3)) acids. EDR induced by acetylcholine (0.1-10 mumol/l) was measured after pre-contraction with noradrenaline. Inhibition of EDR was dose-dependent (0.5-2 mmol/l NEFA), and the greatest inhibition (51%) was observed with stearic acid (2 mmol/l). Lauric acid had the smallest inhibitory effect. The inhibitory effects were always reversible and were evident after 15 min of incubation. Linolenic acid caused a significantly lower inhibition of EDR than stearic acid. SOD (superoxide dismutase) restored the inhibitory effect caused by NEFAs, suggesting the involvement of ROS (reactive oxygen species) in removing nitric oxide. The nitric oxide concentration measured after exposure of the rings to acetylcholine was lower after incubation with NEFAs than with Krebs buffer alone. This finding is consistent with removal of nitric oxide by ROS. This claim was supported by the demonstration of increased concentrations of nitrated tyrosine in the rings incubated with NEFAs.

1H NMR spectrum of the native human insulin monomer. Evidence for conformational differences between the monomer and aggregated forms.

PubMed

Roy, M; Lee, R W; Brange, J; Dunn, M F

1990-04-05

The effects of high dilution on the 1H Fourier transform NMR spectrum of native human insulin at pH* 8.0 and 9.3 have been examined at 500 MHz resolution. The dependence of the spectrum on concentration and comparison with the spectrum of a biologically highly potent monomeric insulin mutant (SerB9----Asp) establish that at 36 microM (pH* 9.3) or 18 microM (pH* 8) and no added buffer or salts, human insulin is monomeric. Under these conditions of dilution, ionic strength, and pH*, human insulin and the SerB9----Asp mutant exhibit nearly identical 1H NMR spectra. At higher concentrations (i.e. greater than 36 microM to 0.91 mM), native human insulin dimerizes, and this aggregation causes a change in insulin conformation. Although there are many changes in the spectrum, the TyrB26 ring H3,5 proton signals located at 6.63 ppm and the methyl signal located at 0.105 ppm (characteristics of monomeric insulin) are particularly distinct signatures of the conformation change that accompanies dimerization. Magnetization transfer experiments show that the 0.105 ppm methyl signal shifts downfield to a new position at 0.45 ppm. We conclude that the 0.105 ppm methyl signal is due to a conformation in which a Leu methyl group is centered over and in van der Waals contact with the ring of an aromatic side chain. Dimerization causes a conformation change that alters this interaction, thereby causing the downfield shift. Nuclear Overhauser studies indicate that the methyl group involved is located within a cluster of aromatic side chains and that the closest ring-methyl group interaction is with the ring of PheB24.

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata

PubMed Central

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-01-01

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research. PMID:28353664

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata.

PubMed

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-03-29

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research.

Development of textured magnesium oxide templates and bicrystals using ion beam assisted deposition

NASA Astrophysics Data System (ADS)

Vallejo, Ronald N.

Recently, there has been an increased research effort in the deposition of near-single-crystal thin films on substrates that do not provide a template for epitaxial crystalline film growth. Ion beam assisted deposition (IBAD) has been demonstrated as one of the most promising methods to artificially control the texture in thin films. Biaxially textured MgO templates of 10 nm thickness were successfully fabricated on glass and silicon substrates without any buffer layers using IBAD. This work has shed insights on several issues. First, surface morphology ˜ 1 nm or better is only a necessary condition for textured IBAD-MgO, but not a sufficient condition. Additional surface preparation must be provided for nucleation and subsequent formation of the textured IBAD-MgO templates. Second, the role of buffer layer on IBAD-MgO texturing. It was found that the ion beam pre-exposure of the substrates prior to IBAD processing provided a sufficient condition for the nucleation and subsequent texture formation of the IBAD grown films. The ion pre-exposure replaced the need for buffer layers in silicon and glass substrates. Finally, by pre-exposing the substrates to Ar + ions, it was found that the ion beam modified the surface and improved the surface roughness of the glass substrates. Textured MgO epi templates were demonstrated for the first time on polymer based substrates (polyimide). This is a crucial step in the realization of epitaxial suspended devices. To achieve an epitaxial film on a sacrificial layer, an epitaxial template film must first be grown prior to subsequent film growth. The role of ion pre-exposure and buffer layer on texture formation was investigated in this part of the work. This thesis also presents groundbreaking results on the fabrication of bicrystal MgO films and bicrystal networks using ion beam assisted deposition. Highly oriented bicrystals, with a common (100) out-of-plane orientation and (110) in-plane orientations having a tilt angle of 45° and 20° have been successfully fabricated. This method has also been used to fabricate two dimensional bicrystal MgO networks in the micrometer scale. The same strategy can be applied to generate nanometer scale bicrystal networks of desired patterns.

Stability analysis of fractional-order Hopfield neural networks with time delays.

PubMed

Wang, Hu; Yu, Yongguang; Wen, Guoguang

2014-07-01

This paper investigates the stability for fractional-order Hopfield neural networks with time delays. Firstly, the fractional-order Hopfield neural networks with hub structure and time delays are studied. Some sufficient conditions for stability of the systems are obtained. Next, two fractional-order Hopfield neural networks with different ring structures and time delays are developed. By studying the developed neural networks, the corresponding sufficient conditions for stability of the systems are also derived. It is shown that the stability conditions are independent of time delays. Finally, numerical simulations are given to illustrate the effectiveness of the theoretical results obtained in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

Seasonal climate signals from multiple tree ring metrics: A case study of Pinus ponderosa in the upper Columbia River Basin

NASA Astrophysics Data System (ADS)

Dannenberg, Matthew P.; Wise, Erika K.

2016-04-01

Projected changes in the seasonality of hydroclimatic regimes are likely to have important implications for water resources and terrestrial ecosystems in the U.S. Pacific Northwest. The tree ring record, which has frequently been used to position recent changes in a longer-term context, typically relies on signals embedded in the total ring width of tree rings. Additional climatic inferences at a subannual temporal scale can be made using alternative tree ring metrics such as earlywood and latewood widths and the density of tree ring latewood. Here we examine seasonal precipitation and temperature signals embedded in total ring width, earlywood width, adjusted latewood width, and blue intensity chronologies from a network of six Pinus ponderosa sites in and surrounding the upper Columbia River Basin of the U.S. Pacific Northwest. We also evaluate the potential for combining multiple tree ring metrics together in reconstructions of past cool- and warm-season precipitation. The common signal among all metrics and sites is related to warm-season precipitation. Earlywood and latewood widths differ primarily in their sensitivity to conditions in the year prior to growth. Total and earlywood widths from the lowest elevation sites also reflect cool-season moisture. Effective correlation analyses and composite-plus-scale tests suggest that combining multiple tree ring metrics together may improve reconstructions of warm-season precipitation. For cool-season precipitation, total ring width alone explains more variance than any other individual metric or combination of metrics. The composite-plus-scale tests show that variance-scaled precipitation reconstructions in the upper Columbia River Basin may be asymmetric in their ability to capture extreme events.

Estimation of oxygen isotope in source water of tree-ring cellulose in Indonesia using tree-ring oxygen isotope model

NASA Astrophysics Data System (ADS)

Hisamochi, R.; Watanabe, Y.; Kurita, N.; Sano, M.; Nakatsuka, T.; Matsuo, M.; Yamamoto, H.; Sugiyama, J.; Tsuda, T.; Tagami, T.

2016-12-01

Oxygen isotope composition (δ18O) of tree-ring cellulose has been used as paleoclimate proxy because its origin is atmospheric precipitation. However, interpretation of tree-ring cellulose δ18O is not simple because source water of tree-ring cellulose (the water took up by tree) is not atmospheric precipitation but soil water or ground water in growing season, precisely. In this study, we investigate the relationship between source water of tree-ring cellulose and precipitation in order to improve interpretation of tree-ring cellulose δ18O as paleoclimate proxy. We collected ten teak (Tectona grandis) plantation samples in Java Island, Indonesia. Teak is deciduous tree and grows in rainy season. Samples were cut into annual rings after cellulose extraction. δ18O of individual rings were measured by TCEA-IRMS at the Research Institute of Humanity and Nature. We calculatedδ18O of source water by means of tree-ring oxygen isotope model and then comparedδ18O of source water and that of monthly atmospheric precipitation at Jakarta (GNIP; Global Network of isotopes in Precipitation). Source waterδ18O shows two types of significant correlation withδ18O in atmospheric precipitation. One is positive correlation withδ18O of atmospheric precipitation in previous rainy season. Another is negative correlation with δ18O of atmospheric precipitation in beginning of the growing season. The former indicates that soil water in growing season contains rainfall in previous rainy season and teak mainly takes it up. The latter is difficult to interpret. It may be related to soil moisutre in beginning of growing season.

Use of FEC coding to improve statistical multiplexing performance for video transport over ATM networks

NASA Astrophysics Data System (ADS)

Kurceren, Ragip; Modestino, James W.

1998-12-01

The use of forward error-control (FEC) coding, possibly in conjunction with ARQ techniques, has emerged as a promising approach for video transport over ATM networks for cell-loss recovery and/or bit error correction, such as might be required for wireless links. Although FEC provides cell-loss recovery capabilities it also introduces transmission overhead which can possibly cause additional cell losses. A methodology is described to maximize the number of video sources multiplexed at a given quality of service (QoS), measured in terms of decoded cell loss probability, using interlaced FEC codes. The transport channel is modelled as a block interference channel (BIC) and the multiplexer as single server, deterministic service, finite buffer supporting N users. Based upon an information-theoretic characterization of the BIC and large deviation bounds on the buffer overflow probability, the described methodology provides theoretically achievable upper limits on the number of sources multiplexed. Performance of specific coding techniques using interlaced nonbinary Reed-Solomon (RS) codes and binary rate-compatible punctured convolutional (RCPC) codes is illustrated.

A network-based approach to disturbance transmission through microbial interactions

PubMed Central

Hunt, Dana E.; Ward, Christopher S.

2015-01-01

Microbes numerically dominate aquatic ecosystems and play key roles in the biogeochemistry and the health of these environments. Due to their short generations times and high diversity, microbial communities are among the first responders to environmental changes, including natural and anthropogenic disturbances such as storms, pollutant releases, and upwelling. These disturbances affect members of the microbial communities both directly and indirectly through interactions with impacted community members. Thus, interactions can influence disturbance propagation through the microbial community by either expanding the range of organisms affected or buffering the influence of disturbance. For example, interactions may expand the number of disturbance-affected taxa by favoring a competitor or buffer the impacts of disturbance when a potentially disturbance-responsive clade’s growth is limited by an essential microbial partner. Here, we discuss the potential to use inferred ecological association networks to examine how disturbances propagate through microbial communities focusing on a case study of a coastal community’s response to a storm. This approach will offer greater insight into how disturbances can produce community-wide impacts on aquatic environments following transient changes in environmental parameters. PMID:26579091

Ex Situ Investigation of Anisotropic Interconnection in Silicon-Titanium-Nickel Alloy Anode Material

DOE PAGES

Cho, Jong -Soo; Alaboina, Pankaj Kumar; Kang, Chan -Soon; ...

2017-03-10

Herein we investigate the nanostructural evolution of Silicon-Titanium-Nickel (Si-Ti-Ni) ternary alloy material synthesized by melt spinning process for advanced lithium-ion battery anode. The synthesized material was found to have nano-Silicon particles dispersed in the Ti 4Ni 4Si 7 (STN) alloy buffering matrix and was characterized by X-ray diffraction (XRD), High resolution- transmission electron microscope (HR-TEM), Scanning transmission electron microscopes - energy dispersive X-ray spectrometer (STEM-EDS), and electrochemical performance test. The role of STN matrix is to accommodate the volume expansion stresses of the dispersed Si nanoparticles. However, an interesting behavior was observed during cycling. The Si nanoparticles were observed tomore » form interconnection channels growing through the weak STN matrix cracks and evolving to a network isolating the STN matrix into small puddles. In conclusion, this unique nanostructural evolution of Si particles and isolation of the STN matrix failing to offer significant buffering effect to the grown Si network eventually accelerates more volume expansions during cycling due to less mechanical confinement and leads to performance degradation and poor cycle stability.« less

Biogeochemical Cycles of Carbon and Sulfur

NASA Technical Reports Server (NTRS)

DesMarais, David J.; DeVincenzi, D. (Technical Monitor)

2002-01-01

The elements carbon (C) and sulfur (S) interact with each other across a network of elemental reservoirs that are interconnected by an array of physical, chemical and biological processes. These networks are termed the biogeochemical C and S cycles. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. The element S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. This presentation describes the modern biogeochemical C and S cycles. Measurements are described whereby stable isotopes can help to infer the nature and quantitative significance of biological and geological processes involved in the C and S cycles. This lecture also summarizes the geological and climatologic aspects of the ancient C and S cycles, as well as the planetary and extraterrestrial processes that influenced their evolution over millions to billions of years.

Synchronization and spatiotemporal patterns in coupled phase oscillators on a weighted planar network

NASA Astrophysics Data System (ADS)

Kagawa, Yuki; Takamatsu, Atsuko

2009-04-01

To reveal the relation between network structures found in two-dimensional biological systems, such as protoplasmic tube networks in the plasmodium of true slime mold, and spatiotemporal oscillation patterns emerged on the networks, we constructed coupled phase oscillators on weighted planar networks and investigated their dynamics. Results showed that the distribution of edge weights in the networks strongly affects (i) the propensity for global synchronization and (ii) emerging ratios of oscillation patterns, such as traveling and concentric waves, even if the total weight is fixed. In-phase locking, traveling wave, and concentric wave patterns were, respectively, observed most frequently in uniformly weighted, center weighted treelike, and periphery weighted ring-shaped networks. Controlling the global spatiotemporal patterns with the weight distribution given by the local weighting (coupling) rules might be useful in biological network systems including the plasmodial networks and neural networks in the brain.

Fragmentation, rings and coarsening: structure and transformations of nanocrystal aggregate networks on a liquid surface

NASA Astrophysics Data System (ADS)

Yang, Bo; Scheidtmann, Jens; Mayer, Joachim; Wuttig, Matthias; Michely, Thomas

2002-01-01

Deposition of Ag on a silicon oil surface leads to the formation of nm-sized Ag crystals floating on the oil surface. These nanocrystals mutually attract each other, forming strongly branched nanocrystal aggregates and continuous aggregate networks. Transformation processes of such nanocrystal aggregate networks are imaged in situ by optical microscopy. The observations are explained on the basis of a simple model involving diffusion of nanocrystals along aggregate edges and the rupture of branches resulting from branch width fluctuations due to edge diffusion.

Nonlinear dynamics of the complex multi-scale network

NASA Astrophysics Data System (ADS)

Makarov, Vladimir V.; Kirsanov, Daniil; Goremyko, Mikhail; Andreev, Andrey; Hramov, Alexander E.

2018-04-01

In this paper, we study the complex multi-scale network of nonlocally coupled oscillators for the appearance of chimera states. Chimera is a special state in which, in addition to the asynchronous cluster, there are also completely synchronous parts in the system. We show that the increase of nodes in subgroups leads to the destruction of the synchronous interaction within the common ring and to the narrowing of the chimera region.

Multi-scale controls of historical forest-fire regimes: new insights from fire-scar networks

Treesearch

Donald A. Falk; Emily K. Heyerdahl; Peter M. Brown; Calvin Farris; Peter Z. Fule; Donald McKenzie; Thomas W. Swetnam; Alan H. Taylor; Megan L. Van Horne

2011-01-01

Anticipating future forest-fire regimes under changing climate requires that scientists and natural resource managers understand the factors that control fire across space and time. Fire scars—proxy records of fires, formed in the growth rings of long-lived trees—provide an annually accurate window into past low-severity fire regimes. In western North America, networks...

GPSS and Modeling of Computer Communication Networks.

DTIC Science & Technology

1982-04-01

chains are used to alter the normal "flows" of transactions in a user defined manner. Transaction "flow" may be controlled on the basis of group ...authors refer to loops and rings interchangeably, including those who have designed loop networks with distributed control mechanisms [8,9,10,11,121...that detailed simulation of character by character transmission does not take place; rather, [ control message--data message-- control message! groupings

Connectivity in a Karst System Using Electrical Resistivity Tomography and Network Theory.

PubMed

Gómez-Nicolás, Mariana; Rebolledo-Vieyra, Mario; Canto-Lugo, Efrain; Huerta-Quintanilla, Rodrigo; Ochoa-Sandoval, Pablo

2017-11-29

The Ring of Cenotes (RC) is an alignment of numerous cenotes (sinkholes) in a semicircular form (with a radius of 100 km) located in northwestern Yucatán, México. The formation roughly coincides with a concentric ring that corresponds to a buried structure, which has been identified as the product of a meteor impact, known as the Chicxulub crater. Secondary permeability generated by the fracturing and faulting of the sedimentary sequence in the Chicxulub crater has favored the karstification process and therefore the development of underground rivers that transport water from the mainland to the sea. This study implements the network theory to study the hydrological connectivity between a group of 11 cenotes within the RC. Eight electrical resistivity tomography transects were used as an empirical basis. Each transect was acquired directly in the field using the SuperSting R1/IP equipment with a dipole-dipole configuration. An adapted version of the reliability algorithm for communication networks was used as a theoretical model. We found evidence of the existence of water cavities in the study area. We made a network from the data and assigned connection probabilities among cenotes as a function of the separation length and the number of water cavities, as well as their size. © 2017, National Ground Water Association.

A flow-control mechanism for distributed systems

NASA Technical Reports Server (NTRS)

Maitan, J.

1991-01-01

A new approach to the rate-based flow control in store-and-forward networks is evaluated. Existing methods display oscillations in the presence of transport delays. The proposed scheme is based on the explicit use of an embedded dynamic model of a store-and-forward buffer in a controller's feedback loop. It is shown that the use of the model eliminates the oscillations caused by the transport delays. The paper presents simulation examples and assesses the applicability of the scheme in the new generation of high-speed photonic networks where transport delays must be considered.

Perceived stress and life satisfaction: social network service use as a moderator.

PubMed

Niu, Qikun; Liu, Yihao; Sheng, Zitong; He, Yue; Shao, Xiaolin

2011-01-01

Social Network Service (SNS) has become a buzzword in recent media coverage with the development of the second generation of Web-based communities. In China, SNS has played an increasingly important role in its users' daily lives, especially among students. With a sample of 471 college students, we tested the direct relationship between perceived stress and life satisfaction using a regression analysis. Moreover, we found SNS use could buffer the negative effect of perceived stress. This study has practical implications on Internet users' SNS use.

Dewetting-mediated pattern formation inside the coffee ring

NASA Astrophysics Data System (ADS)

Li, Weibin; Lan, Ding; Wang, Yuren

2017-04-01

The rearrangement of particles in the final stage of droplet evaporation has been investigated by utilizing differential interference contrast microscopy and the formation mechanism of a network pattern inside a coffee ring has been revealed. A tailored substrate with a circular hydrophilic domain is prepared to obtain thin liquid film containing monolayer particles. Real-time bottom-view images show that the evolution of a dry patch could be divided into three stages: rupture initiation, dry patch expansion, and drying of the residual liquid. A growing number of dry patches will repeat these stages to form the network patterns inside the ringlike stain. It can be shown that the suction effect promotes the rupture of the liquid film and the formation of the dry patch. The particle-assembling process is totally controlled by the liquid film dewetting and dominated by the surface tension of the liquid film, which eventually determine the ultimate deposition patterns.

Topological Nodal-Net Semimetal in a Graphene Network Structure

NASA Astrophysics Data System (ADS)

Wang, Jian-Tao; Nie, Simin; Weng, Hongming; Kawazoe, Yoshiyuki; Chen, Changfeng

2018-01-01

Topological semimetals are characterized by the nodal points in their electronic structure near the Fermi level, either discrete or forming a continuous line or ring, which are responsible for exotic properties related to the topology of bulk bands. Here we identify by ab initio calculations a distinct topological semimetal that exhibits nodal nets comprising multiple interconnected nodal lines in bulk and have two coupled drumheadlike flat bands around the Fermi level on its surface. This nodal net semimetal state is proposed to be realized in a graphene network structure that can be constructed by inserting a benzene ring into each C- C bond in the bct-C4 lattice or by a crystalline modification of the (5,5) carbon nanotube. These results expand the realm of nodal manifolds in topological semimetals, offering a new platform for exploring novel physics in these fascinating materials.

1-(2-Hy-droxy-eth-yl)-3-[(2-hy-droxy-eth-yl)amino]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione.

PubMed

Xie, Zhi-Xiong; Zhao, Sheng-Yin

2011-04-01

There are four molecules in the asymmetric unit of the title compound, C(16)H(17)N(3)O(4), in which the dihedral angles between the indole ring system and maleimide ring are 4.5 (3), 8.3 (3), 8.4 (2) and 10.4 (2)°. In the crystal, mol-ecules are linked by numerous N-H⋯O and O-H⋯O hydrogen bonds, generating a three-dimensional network.

[4-(All­yloxy)phen­yl](phen­yl)methanone

PubMed Central

D’Vries, Richard F.; Grande, Carlos D.; Chaur, Manuel N.; Ellena, Javier A.; Advincula, Rigoberto C.

2014-01-01

The structure of the title compound, C16H14O2, features a dihedral angle of 54.4 (3)° between the aromatic rings. The allyl group is rotated by 37.4 (4)° relative to the adjacent benzene ring. The crystal packing is characterized by numerous C—H⋯O and C—H⋯π inter­actions. Most of these inter­actions occur in layers along (011). The layers are linked by C—H⋯π inter­actions along [100], forming a three-dimensional network. PMID:25161593

2-Nitro­benzyl 2-chloro­acetate

PubMed Central

Zhu, Kai; Liu, Hui; Wang, Yan-Hua; Han, Ping-Fang; Wei, Ping

2009-01-01

In the mol­ecule of the title compound, C9H8ClNO4, an intra­molecular C—H⋯O inter­action results in the formation of a near-planar (r.m.s. deviation 0.002 Å) five-membered ring, which is oriented at a dihedral angle of 4.07 (4)° with respect to the adjacent aromatic ring. In the crystal structure, inter­molecular C—H⋯O inter­actions link the mol­ecules into a two-dimensional network. PMID:21577790

Analysis of the impact of the eastern ring road of Lodz on selected components of the environment

NASA Astrophysics Data System (ADS)

Janas, , Monika; Zawadzka, Alicja

2018-01-01

The geographical location of Poland and the pursuit of economic growth make it necessary to build a sufficiently equipped and compact network of expressways and motorways. Such investments do not, however, leave the environment unaffected. The work analyzes changes that have occurred in the natural environment under the influence of the construction and operation of Lodz eastern ring road being a section of the A1 motorway commissioned in August 2016. Changes in the pollution of air, soil and acoustic climate are discussed in detail.

4-Methyl-N-(1-methyl-1H-indazol-5-yl)benzene-sulfonamide.

PubMed

Chicha, Hakima; Oulemda, Bassou; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C15H15N3O2S, the fused ring system is close to planar, the largest deviation from the mean plane being 0.030 (2) Å, and makes a dihedral angle of 48.84 (9)° with the benzene ring belonging to the methyl-benzene-sulfonamide moiety. In the crystal, mol-ecules are -connected through N-H⋯N hydrogen bonds and weak C-H⋯O contacts, forming a two-dimensional network parallel to (001).

4-Methyl-N-(1-methyl-1H-indazol-5-yl)benzene­sulfonamide

PubMed Central

Chicha, Hakima; Oulemda, Bassou; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C15H15N3O2S, the fused ring system is close to planar, the largest deviation from the mean plane being 0.030 (2) Å, and makes a dihedral angle of 48.84 (9)° with the benzene ring belonging to the methyl­benzene­sulfonamide moiety. In the crystal, mol­ecules are ­connected through N—H⋯N hydrogen bonds and weak C—H⋯O contacts, forming a two-dimensional network parallel to (001). PMID:24427093

N-(3-Chloro-1H-indazol-5-yl)-4-meth­oxy­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C14H12ClN3O3S, the fused five- and six-membered rings are folded slightly along the common edge, forming a dihedral angle of 3.2 (1)°. The mean plane through the indazole system makes a dihedral angle of 30.75 (7)° with the distant benzene ring. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules, forming a two-dimensional network parallel to (001). PMID:24454078

N-(1H-Indazol-5-yl)-4-meth­oxy­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

In the title compound, C14H13N3O3S, the fused ring system is almost planar, the largest deviation from the mean plane being 0.023 (2) Å, and makes a dihedral angle of 47.92 (10)° with the benzene ring of the benzene­sulfonamide moiety. In the crystal, mol­ecules are connected through N—H⋯O hydrogen bonds and weak C—H⋯O contacts, forming a two-dimensional network which is parallel to (010). PMID:24454128

(Z)-3-(1-Chloro-prop-1-en-yl)-2-methyl-1-phenyl-sulfonyl-1H-indole.

PubMed

Umadevi, M; Saravanan, V; Yamuna, R; Mohanakrishnan, A K; Chakkaravarthi, G

2013-11-16

In the title compound, C18H16ClNO2S, the indole ring system forms a dihedral angle of 75.07 (8)° with the phenyl ring. The mol-ecular structure is stabilized by a weak intra-molecular C-H⋯O hydrogen bond. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming a chain along [10-1]. C-H⋯π inter-actions are also observed, leading to a three-dimensional network.

Can positive social exchanges buffer the detrimental effects of negative social exchanges? Age and gender differences.

PubMed

Fiori, Katherine L; Windsor, Tim D; Pearson, Elissa L; Crisp, Dimity A

2013-01-01

Findings from existing research exploring whether positive social exchanges can help to offset (or 'buffer' against) the harmful effects of negative social exchanges on mental health have been inconsistent. This could be because the existing research is characterized by different approaches to studying various contexts of 'cross-domain' and 'within-domain' buffering, and/or because the nature of buffering effects varies according to sociodemographic characteristics that underlie different aspects of social network structure and function. The purpose of this study was to examine whether the buffering effects of global perceptions of positive exchanges on the link between global negative exchanges and mental health varied as a function of age and gender. We used a series of regressions in a sample of 556 Australian older adults (ages 55-94) to test for three-way interactions among gender, positive social exchanges, and negative social exchanges, as well as age and positive and negative social exchanges, in predicting mental health, controlling for years of education, partner status, and physical functioning. We found that positive exchanges buffered against negative exchanges for younger old adults, but not for older old adults, and for women, but not for men. Our findings are interpreted in light of research on individual differences in coping responses and interpersonal goals among late middle-aged and older adults. Our findings are in line with gerontological theories (e.g., socioemotional selectivity theory), and imply that an intervention aimed at using positive social exchanges as a means of coping with negative social exchanges might be more successful among particular populations (i.e., women, 'younger' old adults). Copyright © 2012 S. Karger AG, Basel.

A low-latency high-port count optical switch with optical delay line buffering for disaggregated data centers

NASA Astrophysics Data System (ADS)

Moralis-Pegios, M.; Terzenidis, N.; Mourgias-Alexandris, G.; Vyrsokinos, K.; Pleros, N.

2018-02-01

Disaggregated Data Centers (DCs) have emerged as a powerful architectural framework towards increasing resource utilization and system power efficiency, requiring, however, a networking infrastructure that can ensure low-latency and high-bandwidth connectivity between a high-number of interconnected nodes. This reality has been the driving force towards high-port count and low-latency optical switching platforms, with recent efforts concluding that the use of distributed control architectures as offered by Broadcast-and-Select (BS) layouts can lead to sub-μsec latencies. However, almost all high-port count optical switch designs proposed so far rely either on electronic buffering and associated SerDes circuitry for resolving contention or on buffer-less designs with packet drop and re-transmit procedures, unavoidably increasing latency or limiting throughput. In this article, we demonstrate a 256x256 optical switch architecture for disaggregated DCs that employs small-size optical delay line buffering in a distributed control scheme, exploiting FPGA-based header processing over a hybrid BS/Wavelength routing topology that is implemented by a 16x16 BS design and a 16x16 AWGR. Simulation-based performance analysis reveals that even the use of a 2- packet optical buffer can yield <620nsec latency with >85% throughput for up to 100% loads. The switch has been experimentally validated with 10Gb/s optical data packets using 1:16 optical splitting and a SOA-MZI wavelength converter (WC) along with fiber delay lines for the 2-packet buffer implementation at every BS outgoing port, followed by an additional SOA-MZI tunable WC and the 16x16 AWGR. Error-free performance in all different switch input/output combinations has been obtained with a power penalty of <2.5dB.

Bicarbonate buffered peritoneal dialysis fluid upregulates angiopoietin-1 and promotes vessel maturation.

PubMed

Eich, Gwendolyn; Bartosova, Maria; Tischer, Christian; Wlodkowski, Tanja Tamara; Schaefer, Betti; Pichl, Sebastian; Kraewer, Nicole; Ranchin, Bruno; Vondrak, Karel; Liebau, Max Christoph; Hackert, Thilo; Schmitt, Claus Peter

2017-01-01

Ultrafiltration decline is a progressive issue for patients on chronic peritoneal dialysis (PD) and can be caused by peritoneal angiogenesis induced by PD fluids. A recent pediatric trial suggests better preservation of ultrafiltration with bicarbonate versus lactate buffered fluid; underlying molecular mechanisms are unknown. Angiogenic cytokine profile, tube formation capacity and Receptor Tyrosine Kinase translocation were assessed in primary human umbilical vein endothelial cells following incubation with bicarbonate (BPDF) and lactate buffered (LPDF), pH neutral PD fluid with low glucose degradation product content and lactate buffered, acidic PD fluid with high glucose degradation product content (CPDF). Peritoneal biopsies from age-, PD-vintage- and dialytic glucose exposure matched, peritonitis-free children on chronic PD underwent automated histomorphometry and immunohistochemistry. In endothelial cells angiopoietin-1 mRNA and protein abundance increased 200% upon incubation with BPDF, but decreased by 70% with LPDF as compared to medium control; angiopoietin-2 remained unchanged. Angiopoietin-1/Angiopoietin-2 protein ratio was 15 and 3-fold increased with BPDF compared to LPDF and medium. Time-lapse microscopy with automated network analysis demonstrated less endothelial cell tube formation with BPDF compared to LPDF and CPDF incubation. Receptor Tyrosine Kinase translocated to the cell membrane in BPDF but not in LPDF or CPDF incubated endothelial cells. In children dialyzed with BPDF peritoneal vessels were larger and angiopoietin-1 abundance in CD31 positive endothelium higher compared to children treated with LPDF. Bicarbonate buffered PD fluid promotes vessel maturation via upregulation of angiopoietin-1 in vitro and in children on dialysis. Our findings suggest a molecular mechanism for the observed superior preservation of ultrafiltration capacity with bicarbonate buffered PD fluid with low glucose degradation product content.

HPTN 035 Phase II/IIb Randomized Safety and Effectiveness Study of the Vaginal Microbicides BufferGel and 0.5% PRO 2000 for the Prevention of Sexually Transmitted Infections in Women

PubMed Central

Guffey, M. Bradford; Richardson, Barbra; Husnik, Marla; Makanani, Bonus; Chilongozi, David; Yu, Elmer; Ramjee, Gita; Mgodi, Nyaradzo; Gomez, Kailazarid; Hillier, Sharon L.; Karim, Salim Abdool

2014-01-01

Objectives To estimate the effectiveness of candidate microbicides BufferGel and 0.5% PRO 2000 Gel (P) (PRO 2000) for prevention of non-ulcerative sexually transmitted infections (STIs). Methods Between 2005 and 2007, 3099 women were enrolled in HIV Prevention Trials Network (HPTN) protocol 035, a phase II/IIb evaluation of the safety and effectiveness of BufferGel and PRO 2000 for prevention of sexually transmitted infections, including Neisseria gonorrhoeae (GC), Chlamydia trachomatis (CT), and Trichomonas vaginalis (TV). Incidences of STIs were determined by study arm, and hazard ratios (HRs) of BufferGel and PRO 2000 versus placebo gel or no gel control groups were computed using discrete time Andersen-Gill proportional hazards model. Results The overall incidence rates were 1.6/100 person-years at risk (PYAR) for GC, 3.9/100 PYAR for CT, and 15.3/100 PYAR for TV. For BufferGel versus placebo gel, HRs were 0.99 (95% CI 0.49–2.00), 1.00 (95% CI 0.64–1.57), and 0.95 (95% CI 0.71–1.25) for prevention of GC, CT, and TV respectively. For PRO 2000, HRs were 1.66 (95% CI 0.90–3.06), 1.16 (95% CI 0.76–1.79), and 1.18 (95% CI 0.90–1.53) for prevention of GC, CT, and TV respectively. Conclusions The incidence of STIs was high during HPTN 035 despite provision of free condoms and comprehensive risk-reduction counselling, highlighting the need for effective STI prevention programmes in this population. Unfortunately, candidate microbicides BufferGel and PRO2000 had no protective effect against gonorrhoea, Chlamydia, or trichomoniasis. PMID:24898857

TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: phase diagrams and molecular dynamic simulations.

PubMed

Taha, Mohamed; Lee, Ming-Jer

2013-06-28

Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol∕acetonitrile∕acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

LOFAR for lightning-interferometery and mapping

NASA Astrophysics Data System (ADS)

Scholten, Olaf; Buitink, Stijn; trinh, Gia; Bonardi, Antonio; Corstanje, Arthur; Ebert, Ute; Falcke, Heino; Hoerandel, Joerg; Mitra, Pragati; Mulrey, Katherine; Nelles, Anna; Rachen, Joerg; Rossetto, Laura; Rutjes, Casper; Schellart, Pim; Thoudam, Satayendra; ter Veen, Sander; Winchen, Tobias; Hare, Brian

2017-04-01

We show that a new observation mode at the Low Frequency Array (LOFAR) for Lightning-Interferometery and Mapping (LIM) allows for lightning observations with a resolution that is at least an order of magnitude better than presently operating Lightning Napping Arrays LMAs. Furthermore the polarization of the signal can be used to reconstruct the direction of the discharge. LOFAR, consisting of many thousands of antennas, is a digital radio telescope, primarily build for astronomy observations. The Low Band Antennas (LBA) we use for this work are sensitive to the frequency range of 10 - 90 MHz and consist of two inverted V-shaped dipoles. The antennas are grouped in stations consisting of 48 LBA spread over an area with a diameter of about 30 m for which the relative timing is known accurately. The LOFAR core of approximately 2 km diameter contains 24 such stations located near Exloo in the north of The Netherlands. Remote stations for LIM may lie at a distance of 100 km from the core. Signals are sampled at 200 MS/s (sampling time of 5 ns). All antennas are equipped with ring buffers, that store the raw voltage traces for up to 5 s. When a trigger is received, for example with a lightning flash, the ring buffers are frozen and their contents are copied over the network to a central storage location. We will show an initial analysis of data taken on June 19, 2013, for a thunderstorm at a distance of some 50 km from the telescope. The source location and emission time for each event (lightning step) is found by fitting the arrival times of the pulses for each separate antenna adjusting the station offsets, keeping them the same for all events. The fit reproduces the measurements with an accuracy of about 1 time sample. Interestingly much fine structure is seen in the time-traces and examples will be shown for some events. The time traces for antennas in different stations are very similar and thus not due to noise. We also see a clear polarization-dependent structure for the pulse. The strongly linearly polarized nature of the pulses is corroborated by model calculations showing that this as well as the angular distribution of the emitted radiation can be used to determine the direction of the discharge step. The fine structure of the measured pulse should reflect the time profile of the currents. We are developing an interferometric procedure which will allow us to go beyond single-sample (5 ns) precision to achieve sub-nanosecond timing accuracy. Combined with base-lengths in excess of 50 km this will give us an improvement in resolution by one order of magnitude over existing LMAs. It is of much interest to combine the LOFAR-LIM observations with our recently developed non-invasive method for determining the electric-field in thunderclouds.

Digital video technologies and their network requirements

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. P. Tsang; H. Y. Chen; J. M. Brandt

1999-11-01

Coded digital video signals are considered to be one of the most difficult data types to transport due to their real-time requirements and high bit rate variability. In this study, the authors discuss the coding mechanisms incorporated by the major compression standards bodies, i.e., JPEG and MPEG, as well as more advanced coding mechanisms such as wavelet and fractal techniques. The relationship between the applications which use these coding schemes and their network requirements are the major focus of this study. Specifically, the authors relate network latency, channel transmission reliability, random access speed, buffering and network bandwidth with the variousmore » coding techniques as a function of the applications which use them. Such applications include High-Definition Television, Video Conferencing, Computer-Supported Collaborative Work (CSCW), and Medical Imaging.« less

A low-cost photonic biosensor built on a polymer platform

NASA Astrophysics Data System (ADS)

Wang, Linghua; Kodeck, Valérie; Van Vlierberghe, Sandra; Ren, Jun; Teng, Jie; Han, Xiuyou; Jian, Xigao; Baets, Roel; Morthier, Geert; Zhao, Mingshan

2011-12-01

Planar integrated optical biosensors are becoming more and more important as they facilitate label-free and real time monitoring biosensing with high sensitivity. In this paper, the systematic research on one kind of optical biosensor, based on a resonant principle in a polymer ring resonator, will be presented. Reduced footprint and high sensitivity are advantages of this kind of biosensor. Rather than expensive CMOS fabrication, the device with high performance is fabricated through a simple UV based soft imprint technique utilizing self-developed low loss polymer material. The measurement results for the bulk sensing of a NaCl solution and the surface sensing of a minimal amount of avidin molecules in a buffered solution will be presented.

Superconducting YBa2Cu3O7- δ Thin Film Detectors for Picosecond THz Pulses

NASA Astrophysics Data System (ADS)

Probst, P.; Scheuring, A.; Hofherr, M.; Wünsch, S.; Il'in, K.; Semenov, A.; Hübers, H.-W.; Judin, V.; Müller, A.-S.; Hänisch, J.; Holzapfel, B.; Siegel, M.

2012-06-01

Ultra-fast THz detectors from superconducting YBa2Cu3O7- δ (YBCO) thin films were developed to monitor picosecond THz pulses. YBCO thin films were optimized by the introduction of CeO2 and PrBaCuO buffer layers. The transition temperature of 10 nm thick films reaches 79 K. A 15 nm thick YBCO microbridge (transition temperature—83 K, critical current density at 77 K—2.4 MA/cm2) embedded in a planar log-spiral antenna was used to detect pulsed THz radiation of the ANKA storage ring. First time resolved measurements of the multi-bunch filling pattern are presented.

The influence of neighborhood food stores on change in young girls' body mass index.

PubMed

Leung, Cindy W; Laraia, Barbara A; Kelly, Maggi; Nickleach, Dana; Adler, Nancy E; Kushi, Lawrence H; Yen, Irene H

2011-07-01

As the prevalence of childhood obesity has risen in past decades, more attention has been given to how the neighborhood food environment affects children's health outcomes. This exploratory study examined the relationship between the presence of neighborhood food stores within a girl's neighborhood and 3-year risk of overweight/obesity and change in BMI, in girls aged 6 or 7 years at baseline. A longitudinal analysis of participants in the Cohort Study of Young Girls' Nutrition, Environment and Transitions (CYGNET) was conducted from 2005 to 2008. Neighborhood food stores were identified from a commercial database and classified according to industry codes in 2006. Generalized linear and logistic models were used to examine how availability of food stores within 0.25-mile and 1.0-mile network buffers of a girl's residence were associated with BMI z-score change and risk of overweight or obesity, adjusting for baseline BMI/weight and family sociodemographic characteristics. Data were analyzed in 2010. Availability of convenience stores within a 0.25-mile network buffer of a girl's residence was associated with greater risk of overweight/obesity (OR=3.38, 95% CI=1.07, 10.68) and an increase in BMI z-score (β=0.13, 95% CI=0.00, 0.25). Availability of produce vendors/farmer's markets within a 1.0-mile network buffer of a girl's residence was inversely associated with overweight/obesity (OR=0.22, 95% CI=0.05, 1.06). A significant trend was observed between availability of produce vendors/farmer's markets and lower risk of overweight/obesity after 3 years. Although food store inventories were not assessed and food store indices were not created, the availability of neighborhood food stores may affect a young girl's weight trajectory over time. Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

The Influence of Neighborhood Food Stores on Change in Young Girls’ Body Mass Index

PubMed Central

Leung, Cindy W.; Laraia, Barbara A.; Kelly, Maggi; Nickleach, Dana; Adler, Nancy E.; Kushi, Lawrence H.; Yen, Irene H.

2011-01-01

Background As the prevalence of childhood obesity has risen in past decades, more attention has been given to how the neighborhood food environment affects children’s health outcomes. Purpose This exploratory study examined the relationship between the presence of neighborhood food stores within a girl’s neighborhood and 3-year risk of overweight/obesity and change in BMI, in girls aged 6 or 7 years at baseline. Methods A longitudinal analysis of participants in the Cohort Study of Young Girls’ Nutrition, Environment and Transitions (CYGNET) was conducted from 2005–2008. Neighborhood food stores were identified from a commercial database and classified according to industry codes in 2006. Generalized linear and logistic models were used to examine how availability of food stores within 0.25-mile and 1.0-mile network buffers of a girl’s residence were associated with BMI z-score change and risk of overweight or obesity, adjusting for baseline BMI/weight and family sociodemographic characteristics. Data were analyzed in 2010. Results Availability of convenience stores within a 0.25-mile network buffer of a girl’s residence was associated with greater risk of overweight/obesity (OR 3.38, 95% CI 1.07, 10.68) and an increase in BMI z-score (β=0.13, 95% CI 0.00, 0.25). Availability of produce vendors/farmer’s markets within a 1.0-mile network buffer of a girl’s residence was inversely associated with overweight/ obesity (OR 0.22, 95% CI 0.05, 1.06). A significant trend was observed between availability of produce vendors/farmer’s markets and lower risk of overweight/obesity after 3 years. Conclusions Although food store inventories were not assessed and food store indices were not created, the availability of neighborhood food stores may affect a young girl’s weight trajectory over time. PMID:21665062

Tree growth and vegetation activity at the ecosystem-scale in the eastern Mediterranean

NASA Astrophysics Data System (ADS)

Coulthard, Bethany L.; Touchan, Ramzi; Anchukaitis, Kevin J.; Meko, David M.; Sivrikaya, Fatih

2017-08-01

Linking annual tree growth with remotely-sensed terrestrial vegetation indices provides a basis for using tree rings as proxies for ecosystem primary productivity over large spatial and long temporal scales. In contrast with most previous tree ring/remote sensing studies that have focused on temperature-limited boreal and taiga environments, here we compare the normalized difference vegetation index (NDVI) with a network of Pinus brutia tree ring width chronologies collected along ecological gradients in semiarid Cyprus, where both radial tree growth and broader vegetation activity are controlled by drought. We find that the interaction between precipitation, elevation, and land-cover type generate a relationship between radial tree growth and NDVI. While tree ring chronologies at higher-elevation forested sites do not exhibit climate-driven linkages with NDVI, chronologies at lower-elevation dry sites are strongly correlated with NDVI during the winter precipitation season. At lower-elevation sites, land cover is dominated by grasslands and shrublands and tree ring widths operate as a proxy for ecosystem-scale vegetation activity. Tree rings can therefore be used to reconstruct productivity in water-limited grasslands and shrublands, where future drought stress is expected to alter the global carbon cycle, biodiversity, and ecosystem functioning in the 21st century.

In situ synthesis of di-n-butyl l-tartrate-boric acid complex chiral selector and its application in chiral microemulsion electrokinetic chromatography.

PubMed

Hu, Shaoqiang; Chen, Yonglei; Zhu, Huadong; Zhu, Jinhua; Yan, Na; Chen, Xingguo

2009-11-06

A novel procedure for in situ assembling a complex chiral selector, di-n-butyl l-tartrate-boric acid complex, by the reaction of di-n-butyl l-tartrate with boric acid in a running buffer was reported and its application in the enantioseparation of beta-blockers and structural related compounds by chiral microemulsion electrokinetic chromatography (MEEKC) has been demonstrated. In order to achieve a good enantioseparation, the effect of dibutyl l-tartrate and sodium tetraborate concentration, surfactant identity and concentration, cosurfactant, buffer pH and composition, organic modifiers, as well as applied voltage and capillary length were investigated. Ten pairs of enantiomers that could not be separated with only dibutyl l-tartrate, obtained good chiral separation using the complex chiral selector; among them, seven pairs could be baseline resolved under optimized experimental conditions. The fixation of chiral centers by the formation of five-membered rings, and being oppositely charged with basic analytes were thought to be the key factors giving the complex chiral selector a superior chiral recognition capability. The effect of the molecular structure of analytes on enantioseparation was discussed in terms of molecular interaction.

The role of Ag buffer layer in Fe islands growth on Ge (111) surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Tsu-Yi, E-mail: phtifu@phy.ntnu.edu.tw; Wu, Jia-Yuan; Jhou, Ming-Kuan

2015-05-07

Sub-monolayer iron atoms were deposited at room temperature on Ge (111)-c(2 × 8) substrates with and without Ag buffer layers. The behavior of Fe islands growth was investigated by using scanning tunneling microscope (STM) after different annealing temperatures. STM images show that iron atoms will cause defects and holes on substrates at room temperature. As the annealing temperature rises, iron atoms pull out germanium to form various kinds of alloyed islands. However, the silver layer can protect the Ag/Ge(111)-(√3×√3) reconstruction from forming defects. The phase diagram shows that ring, dot, and triangular defects were only found on Ge (111)-c(2 × 8) substrates. The kindsmore » of islands found in Fe/Ge system are similar to Fe/Ag/Ge system. It indicates that Ge atoms were pulled out to form islands at high annealing temperatures whether there was a Ag layer or not. But a few differences in big pyramidal or strip islands show that the silver layer affects the development of islands by changing the surface symmetry and diffusion coefficient. The structure characters of various islands are also discussed.« less

An unusually strong Einstein ring in the radio source PKS1830 - 211

NASA Technical Reports Server (NTRS)

Jauncey, D. L.; Reynolds, J. E.; Tzioumis, A. K.; Murphy, D. W.; Preston, R. A.; Jones, D. L.; Meier, D. L.; Hoard, D. W.; Lobdell, E. T.; Skjerve, L.

1991-01-01

High-resolution radio images of PKS1830 - 211 are obtained to study the possibility that the double structure is a gravitationally lensed object. The VLBI observations, taken from interferometric radiotelescope networks, reveal an elliptical ring that connects two bright spots of similar composition. Because the lens and the lensed object are closely aligned, and because of the structure of the two spots, the source is concluded to be a radio Einstein ring. The source is found to be close to the galactic plane, and the lens and the lensed object are extragalactic. The source is also found to be unusually bright, suggesting that it is aligned with a bright background source or amplified by some mechanism related to a source that is not so bright.

Impact of fiber ring laser configuration on detection capabilities in FBG based sensor systems

NASA Astrophysics Data System (ADS)

Osuch, Tomasz; Kossek, Tomasz; Markowski, Konrad

2014-11-01

In this paper fiber ring lasers (FRL) as interrogation units for distributed fiber Bragg grating (FBG) based sensor networks are studied. In particular, two configurations of the fiber laser with erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA) as gain medium were analyzed. In the case of EDFA-based fiber interrogation systems, CW as well as active-mode locking operation were taken into account. The influence of spectral overlapping of FBGs spectra on detection capabilities of examined FRLs are presented. Experimental results show that the SOA-based fiber laser interrogation unit can operate as a multi-parametric sensing system. In turn, using an actively mode-locked fiber ring laser with an EDFA, an electronically switchable FBG based sensing system can be realized.

Crystal structure of N-(1-allyl-3-chloro-4-eth­oxy-1H-indazol-5-yl)-4-meth­oxybenzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

In the title compound, C19H20ClN3O4S, the benzene ring is inclined to the indazole ring system (r.m.s. deviation = 0.014 Å) by 65.07 (8)°. The allyl and eth­oxy groups are almost normal to the indazole ring, as indicated by the respective torsion angles [N—N—C—C = 111.6 (2) and C—C—O—C = −88.1 (2)°]. In the crystal, mol­ecules are connected by N—H⋯N hydrogen bonds, forming helical chains propagating along [010]. The chains are linked by C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:25309208

Dimethyl 4-[3-(4-meth­oxy­phen­yl)-1-phenyl-1H-pyrazol-4-yl]-2,6-dimethyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate dihydrate

PubMed Central

Fun, Hoong-Kun; Ooi, Chin Wei; Garudachari, B.; Shivananda, Kammasandra Nanjunda; Isloor, Arun M.

2012-01-01

In the title compound, C27H27N3O5·2H2O, the dihydro­pyridine ring adopts a flattened boat conformation. The central pyrazole ring is essentially planar [maximum deviation of 0.003 (1) Å] and makes dihedral angles of 50.42 (6) and 26.44 (6)° with the benzene rings. In the crystal, mol­ecules are linked via N—H⋯O, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds into two-dimensional networks parallel to the bc plane. The crystal structure is further consolidated by weak C—H⋯π inter­actions. PMID:22798871

Recovery Act: Energy Efficiency of Data Networks through Rate Adaptation (EEDNRA) - Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthew Andrews; Spyridon Antonakopoulos; Steve Fortune

2011-07-12

This Concept Definition Study focused on developing a scientific understanding of methods to reduce energy consumption in data networks using rate adaptation. Rate adaptation is a collection of techniques that reduce energy consumption when traffic is light, and only require full energy when traffic is at full provisioned capacity. Rate adaptation is a very promising technique for saving energy: modern data networks are typically operated at average rates well below capacity, but network equipment has not yet been designed to incorporate rate adaptation. The Study concerns packet-switching equipment, routers and switches; such equipment forms the backbone of the modern Internet.more » The focus of the study is on algorithms and protocols that can be implemented in software or firmware to exploit hardware power-control mechanisms. Hardware power-control mechanisms are widely used in the computer industry, and are beginning to be available for networking equipment as well. Network equipment has different performance requirements than computer equipment because of the very fast rate of packet arrival; hence novel power-control algorithms are required for networking. This study resulted in five published papers, one internal report, and two patent applications, documented below. The specific technical accomplishments are the following: • A model for the power consumption of switching equipment used in service-provider telecommunication networks as a function of operating state, and measured power-consumption values for typical current equipment. • An algorithm for use in a router that adapts packet processing rate and hence power consumption to traffic load while maintaining performance guarantees on delay and throughput. • An algorithm that performs network-wide traffic routing with the objective of minimizing energy consumption, assuming that routers have less-than-ideal rate adaptivity. • An estimate of the potential energy savings in service-provider networks using feasibly-implementable rate adaptivity. • A buffer-management algorithm that is designed to reduce the size of router buffers, and hence energy consumed. • A packet-scheduling algorithm designed to minimize packet-processing energy requirements. Additional research is recommended in at least two areas: further exploration of rate-adaptation in network switching equipment, including incorporation of rate-adaptation in actual hardware, allowing experimentation in operational networks; and development of control protocols that allow parts of networks to be shut down while minimizing disruption to traffic flow in the network. The research is an integral part of a large effort within Bell Laboratories, Alcatel-Lucent, aimed at dramatic improvements in the energy efficiency of telecommunication networks. This Study did not explicitly consider any commercialization opportunities.« less

xQuake: A Modern Approach to Seismic Network Analytics

NASA Astrophysics Data System (ADS)

Johnson, C. E.; Aikin, K. E.

2017-12-01

While seismic networks have expanded over the past few decades, and social needs for accurate and timely information has increased dramatically, approaches to the operational needs of both global and regional seismic observatories have been slow to adopt new technologies. This presentation presents the xQuake system that provides a fresh approach to seismic network analytics based on complexity theory and an adaptive architecture of streaming connected microservices as diverse data (picks, beams, and other data) flow into a final, curated catalog of events. The foundation for xQuake is the xGraph (executable graph) framework that is essentially a self-organizing graph database. An xGraph instance provides both the analytics as well as the data storage capabilities at the same time. Much of the analytics, such as synthetic annealing in the detection process and an evolutionary programing approach for event evolution, draws from the recent GLASS 3.0 seismic associator developed by and for the USGS National Earthquake Information Center (NEIC). In some respects xQuake is reminiscent of the Earthworm system, in that it comprises processes interacting through store and forward rings; not surprising as the first author was the lead architect of the original Earthworm project when it was known as "Rings and Things". While Earthworm components can easily be integrated into the xGraph processing framework, the architecture and analytics are more current (e.g. using a Kafka Broker for store and forward rings). The xQuake system is being released under an unrestricted open source license to encourage and enable sthe eismic community support in further development of its capabilities.

pH-based fiber optic biosensors for use in clinical and biotechnological applications

NASA Astrophysics Data System (ADS)

Mueller, Cord; Hitzmann, Bernd; Schubert, Florian; Scheper, Thomas

1995-05-01

The development of pH-based fiber optic biosensors and their uses in clinical and biotechnological applications are described. Based on a pH-sensitive optode, different biosensors for urea, penicillin, glucose and creatinine were developed. A multichannel modular fluorimeter was used to measure signals from up to three optodes simultaneously. The pH value and the buffer capacity are critical factors for biosensors based on pH probes and influence the biosensor signal. A flow injection analysis (FIA) system is used to eliminate the latter influences. With this integrated system, samples can be analyzed sequentially by the injection of a defined volume of each sample into a continuously flowing buffer stream that transports the samples to the sensors. The complex signal is transformed and analyzed by a computer system. Characteristic features of the FIA peak give information about the buffer capacity in the solution. With the help of intelligent computing (neural networks) it is possible to recognize these features and relate them to the respective buffer capacity to obtain more accurate values. Various applications of these biosensors are discussed. The pH optode is also used to monitor enzymatic reactions in non aqueous solvents. In this case the production of acetic acid can be detected on line.

5-Chloro-5''-[4-(di-methyl-amino)-benzyl-idene]-4'-[4-(di-methyl-amino)-phen-yl]-1',1''-di-methyl-dispiro-[indoline-3,2'-pyrrolidine-3',3''-piperidine]-2,4''-dione.

PubMed

Farag, I S Ahmed; Girgis, Adel S; Ramadan, A A; Moustafa, A M; Tiekink, Edward R T

2014-01-01

The title compound, C34H38ClN5O2, has spiro links connecting the pyrrolidine ring and indole residue, as well as the piperidine and pyrrolidine rings. A half-chair conformation is found for the piperidine ring with the C atom connected to the spiro-C atom lying 0.738 (4) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.0407 Å). The methyl-ene C atom is the flap in the envelope conformation for the pyrrolidine ring. In the crystal, supra-molecular chains are sustained by alternating eight-membered {⋯HNCO}2 and 14-membered {⋯HC5O}2 synthons. Chains are connected into a three-dimensional network by (pyrrolidine-bound phenyl-meth-yl)C-H⋯π(pyrrolidine-bound phen-yl) edge-to-face inter-actions.

Classifying quantum entanglement through topological links

NASA Astrophysics Data System (ADS)

Quinta, Gonçalo M.; André, Rui

2018-04-01

We propose an alternative classification scheme for quantum entanglement based on topological links. This is done by identifying a nonrigid ring to a particle, attributing the act of cutting and removing a ring to the operation of tracing out the particle, and associating linked rings to entangled particles. This analogy naturally leads us to a classification of multipartite quantum entanglement based on all possible distinct links for a given number of rings. To determine all different possibilities, we develop a formalism that associates any link to a polynomial, with each polynomial thereby defining a distinct equivalence class. To demonstrate the use of this classification scheme, we choose qubit quantum states as our example of physical system. A possible procedure to obtain qubit states from the polynomials is also introduced, providing an example state for each link class. We apply the formalism for the quantum systems of three and four qubits and demonstrate the potential of these tools in a context of qubit networks.

Performance of highly connected photonic switching lossless metro-access optical networks

NASA Astrophysics Data System (ADS)

Martins, Indayara Bertoldi; Martins, Yara; Barbosa, Felipe Rudge

2018-03-01

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The "lossless" photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

Mobility and Congestion in Dynamical Multilayer Networks with Finite Storage Capacity

NASA Astrophysics Data System (ADS)

Manfredi, S.; Di Tucci, E.; Latora, V.

2018-02-01

Multilayer networks describe well many real interconnected communication and transportation systems, ranging from computer networks to multimodal mobility infrastructures. Here, we introduce a model in which the nodes have a limited capacity of storing and processing the agents moving over a multilayer network, and their congestions trigger temporary faults which, in turn, dynamically affect the routing of agents seeking for uncongested paths. The study of the network performance under different layer velocities and node maximum capacities reveals the existence of delicate trade-offs between the number of served agents and their time to travel to destination. We provide analytical estimates of the optimal buffer size at which the travel time is minimum and of its dependence on the velocity and number of links at the different layers. Phenomena reminiscent of the slower is faster effect and of the Braess' paradox are observed in our dynamical multilayer setup.

Mobility and Congestion in Dynamical Multilayer Networks with Finite Storage Capacity.

PubMed

Manfredi, S; Di Tucci, E; Latora, V

2018-02-09

Multilayer networks describe well many real interconnected communication and transportation systems, ranging from computer networks to multimodal mobility infrastructures. Here, we introduce a model in which the nodes have a limited capacity of storing and processing the agents moving over a multilayer network, and their congestions trigger temporary faults which, in turn, dynamically affect the routing of agents seeking for uncongested paths. The study of the network performance under different layer velocities and node maximum capacities reveals the existence of delicate trade-offs between the number of served agents and their time to travel to destination. We provide analytical estimates of the optimal buffer size at which the travel time is minimum and of its dependence on the velocity and number of links at the different layers. Phenomena reminiscent of the slower is faster effect and of the Braess' paradox are observed in our dynamical multilayer setup.

In vitro and ex vivo angiogenic effects of roxarsone on rat endothelial cells.

PubMed

Zhu, Jiaqiao; Cui, Weibo; Liu, Xue; Ying, Jun; Hu, Chengyun; Zhang, Yumei

2013-11-25

Roxarsone, a feed additive, is being used worldwide to promote animal growth. However, the potential effect of roxarsone on angiogenesis has not been extensively characterized. We examined the ability of roxarsone to promote angiogenesis of rat endothelial cells in vitro and from rat aorta rings ex vivo. Endothelial cells from rats were exposed to 0.01-10.00μM roxarsone, 5ng/mL vascular endothelial growth factor (VEGF) as a positive control or phosphate buffer saline (PBS) as a negative control. Cell proliferation was measured by MTT assay, and the content of VEGF in supernatants was measured by enzyme-linked immunosorbent assay and Western blotting. A Matrigel-induced tube formation assay was used to evaluate the effects of roxarsone on endothelial cells. Additionally, the total number and length of microvessels sprouted from rat aortic rings were measured for ex vivo investigation of angiogenesis. Results showed that the cell viability and total number and length of capillary-like tube formations after roxarsone treatment was significantly higher than that of negative (P<0.05), with a maximum effect at 1.00μM exposure. Furthermore, the number of microvessels sprouted from aortic rings treated for 4h with 0.1-10.0μM roxarsone was significantly higher than that of PBS treatment, with a peak value of 1.0μM. These results further demonstrate the potential of roxarsone to promote angiogenesis in vitro and ex vivo. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Advanced helium purge seals for Liquid Oxygen (LOX) turbopumps

NASA Technical Reports Server (NTRS)

Shapiro, Wilbur; Lee, Chester C.

1989-01-01

Program objectives were to determine three advanced configurations of helium buffer seals capable of providing improved performance in a space shuttle main engine (SSME), high-pressure liquid oxygen (LOX) turbopump environment, and to provide NASA with the analytical tools to determine performance of a variety of seal configurations. The three seal designs included solid-ring fluid-film seals often referred to as floating ring seals, back-to-back fluid-film face seals, and a circumferential sectored seal that incorporated inherent clearance adjustment capabilities. Of the three seals designed, the sectored seal is favored because the self-adjusting clearance features accommodate the variations in clearance that will occur because of thermal and centrifugal distortions without compromising performance. Moreover, leakage can be contained well below the maximum target values; minimizing leakage is important on the SSME since helium is provided by an external tank. A reduction in tank size translates to an increase in payload that can be carried on board the shuttle. The computer codes supplied under this program included a code for analyzing a variety of gas-lubricated, floating ring, and sector seals; a code for analyzing gas-lubricated face seals; a code for optimizing and analyzing gas-lubricated spiral-groove face seals; and a code for determining fluid-film face seal response to runner excitations in as many as five degrees of freedom. These codes proved invaluable for optimizing designs and estimating final performance of the seals described.

Dehydration and Stabilization of a Reactive Tertiary Hydroxyl Group in Solid Oral Dosage Forms of BMS-779788.

PubMed

Adams, Monica L; Sharma, Vijayata; Gokhale, Madhushree; Huang, Yande; Stefanski, Kevin; Su, Ching; Hussain, Munir A

2016-04-01

BMS-779788 contains a reactive tertiary hydroxyl attached to a weakly basic imidazole ring. Propensity of the carbinol toward dehydration to yield the corresponding alkene, BMS-779788-ALK, was evaluated. Elevated levels of BMS-779788-ALK were observed in excipient compatibility samples. Stability studies revealed that BMS-779788 degrades to BMS-779788-ALK in capsules and tablets prepared by both dry and wet granulation processes. An acid-catalyzed dehydration mechanism, in which the heterocyclic core contributes resonance stability to the cationic intermediate via charge transfer to the imidazole ring, was proposed. Therefore, neutralization via a buffered (pH 7.0) granulating solution was used to mitigate dehydration. Solution studies revealed degradation of BMS-779788 to BMS-779788-ALK over the pH range of 1-7.5. Reversibility was confirmed by initiating reactions with BMS-779788-ALK over the same pH range. Accordingly, a simple reversible scheme can be used to describe reactions initiated with either BMS-779788 or BMS-779788-ALK. To eliminate potential for charge delocalization across the heterocycle and probe the degradation mechanism, the imidazole ring of BMS-779788 was methylated (BMS-779788-Me). The propensity for acid-catalyzed dehydration was then evaluated. The acid stability of BMS-779788-Me confirmed that the heterocyclic core contributes to reactivity liability of the tertiary hydroxyl. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Reducing sediment inputs to Scottish streams: a review of the efficacy of soil conservation practices in upland forestry.

PubMed

Carling, P A; Irvine, B J; Hill, A; Wood, M

2001-01-29

The historical process by which a soil conservation strategy has evolved within the UK forestry industry is briefly reviewed. Particular attention is given to the development of practical and effective guidelines to prevent both soil damage and sediment entering water courses. It is concluded that the 'Forest and Water Guidelines', together with other forest industry manuals, largely provide adequate protection for aquatic habitats from pre-afforestation cultivation and from harvesting activities. The problem of soil erosion owing to ploughing of open furrows has largely been obviated by improved drainage network design coupled with the use of vegetated buffer strips and sediment catchpits. Alternative site preparation techniques, such as 'moling' or 'dolloping' of afforestation sites, are now preferred. However, the effects on slope hydrology and the improved soil conservation associated with these methods require quantifying. Additional understanding of effective buffer strip function, for example, on a variety of slope angles, soil types and vegetation associations would be beneficial. The design of forest roads and the associated network of drains, culverts and sediment catchpits is addressed in forestry guidelines. Future potential in this area may involve the use of Geographical Information Systems in the effective design of road networks which minimise adverse effects on slope hydrology. Similarly computer simulation of flow routing might aid in the design of road drain networks. At the more local scale there remains scope for further research aimed at minimising soil disturbance by machinery. Consideration should also be given to the long-term sustainability of the soil structure through second and subsequent crop rotations.

Social Support and Networks: Cardiovascular Responses Following Recall on Immigration Stress Among Chinese Americans

PubMed Central

Suchday, Sonia; Wylie-Rosett, Judith

2014-01-01

Social support has been shown to act as a buffer for cardiovascular responses to stress. However, little is known about how social support and networks are related to cardiovascular responses to immigration stress recall. The current study evaluated the impact of structural and functional support on cardiovascular reaction following immigrant stress recall provocation as well as the moderation effect of interdependent self-construal among first-generation Chinese immigrants. One hundred fifty Chinese immigrants were recruited in the New York Chinatown area. Participants completed questionnaires assessing their levels of social support and networks, and interdependent self-construal. Following adaptation, participants recalled a recent post-immigration stress-provoking situation. Cardiovascular measures were taken during adaptation, stressor task, and recovery period. Hierarchical multiple regression analysis was performed. Social network size and type, as well as perceived emotional support were positively predictive of systolic blood pressure (SBP) reactivity changes. Instrumental support seeking was a positive predictor of SBP and diastolic blood pressure (DBP) reactivity. The moderation effect between instrumental support seeking and interdependent self-construal were significantly predictive of DBP reactivity and recovery, suggesting that perceptions about themselves in relation to others is a crucial factor for determining whether support seeking is beneficial or not. Social support was not a direct buffer on cardiovascular responses to stress among Chinese immigrants. Chinese values of interdependence and collectivism may partly explain the disconfirming results. Still, when interdependent self-construal was taken into account, Chinese immigrants who had less interdependent self-construal, but solicited more instrumental support, had faster adaptation to stress over the long term. PMID:24288021

A generalized approach to complex networks

NASA Astrophysics Data System (ADS)

Costa, L. Da F.; da Rocha, L. E. C.

2006-03-01

This work describes how the formalization of complex network concepts in terms of discrete mathematics, especially mathematical morphology, allows a series of generalizations and important results ranging from new measurements of the network topology to new network growth models. First, the concepts of node degree and clustering coefficient are extended in order to characterize not only specific nodes, but any generic subnetwork. Second, the consideration of distance transform and rings are used to further extend those concepts in order to obtain a signature, instead of a single scalar measurement, ranging from the single node to whole graph scales. The enhanced discriminative potential of such extended measurements is illustrated with respect to the identification of correspondence between nodes in two complex networks, namely a protein-protein interaction network and a perturbed version of it.

Season-specific climate signal and reconstruction from a new tree-ring network in the southwestern U.S

NASA Astrophysics Data System (ADS)

Griffin, D.; Woodhouse, C. A.; Meko, D. M.; Stahle, D. W.; Faulstich, H.; Leavitt, S. W.; Touchan, R.; Castro, C. L.; Carrillo, C.

2011-12-01

Our research group has updated existing tree-ring collections from over 50 sampling sites in the southwestern U.S. The new and archived specimens, carefully dated with dendrochronology, have been analyzed for width variations of "earlywood" and "latewood." These are the two components of annual rings in conifers that form in spring and summer, respectively. The network of primary tree-ring data has been used to develop a suite of well-replicated chronologies that extend through the 2008 growing season and are sensitive to the season-specific climate variability of the Southwest. Correlation function analysis indicates that the earlywood chronologies are closely related to cool season (October-April) precipitation variability and the chronologies derived from latewood are generally sensitive to precipitation and temperature conditions during the warm season (June-August). These proxy data originate from biological organisms and are not without bias; however, they do constitute a new means for evaluating the recent paleoclimatic history of the North American summer monsoon. The monsoon is a major component of the region's climate, impacting social and environmental systems and delivering up to 60% of the annual precipitation in the southwestern U.S. We have developed latewood-based retrodictions of monsoon precipitation that explain over half of the variance in the instrumental record, pass standard verification tests, and point to periods of persistent drought and wetness during the last 300-500 years. These reconstructions are being used to evaluate the monsoon's long-term spatiotemporal variability and its relationship to cool season climate and the major modes of ocean-atmosphere variability.

Ring distributions in alkali- and alkaline-earth aluminosilicate framework glasses- a raman spectroscopic study

USGS Publications Warehouse

Sharma, S.K.; Philpotts, J.A.; Matson, D.W.

1985-01-01

Raman spectra of crystalline polymorphs of a number of tectosilicate minerals having various sizes of smallest rings of TO4 tetrahedra (T = Si, Al) have been investigated to identify the bands that are sensitive indicators of the smallest rings in the network. The information obtained from the Raman spectra of tectosilicate minerals (e.g., SiO2 polymorphs, NaAlSi3O8 (Ab), NaAlSiO4 (Ne), KAlSi3O8 (Or), and KAlSi2O6 (Lc)) is used to interpret the Raman spectra of the isochemical glasses. It is shown that the frequency of the dominant ??s (TOT) band in the spectra of both crystals and glasses is related to the dominant size of TO4 rings in the structure. In agreement with previous X-ray RDF work, it is found that in the glasses of Ab and Jd (NaAlSi2O6) compositions, six-membered rings of TO4 tetrahedra predominate. The Raman spectrum of Or glass, however, indicates that clusters of intermixed four- and six-membered rings of TO4 tetrahedra, similar to those existing in crystalline leucite, are also present in the glass. Raman evidence indicates that four-membered rings of TO4 tetrahedra predominate in the glass of An composition. Similarly, the higher frequency of the ??s (TOT) band in the spectrum of Ne glass as compared with the frequency the ??s (TOT) band in the spectra of crystalline cargenieite and nephelite indicates either an admixture of the four- and six-membered rings or the puckering of six-membered rings in the glass structure. ?? 1985.

Wetland Suitability and Connectivity for Trans-Saharan Migratory Waterbirds

PubMed Central

Teunen, Joachim; Saura, Santiago; Koedam, Nico

2015-01-01

To complete their life cycle waterbirds rely on patchily distributed and often ephemeral wetlands along their migration route in a vast unsuitable matrix. However, further loss and degradation of remaining wetland habitats might lead to a configuration and size of stopovers that is no longer sufficient to ensure long-term survival of waterbird populations. By identifying optimal conservation targets to maintain overall habitat availability en route, we can accommodate an as yet absent functional connectivity component in larger management frameworks for migratory waterbirds, such as the Ramsar Convention and the EU Natura 2000 Network. Using a graph-based habitat availability metric (Equivalent Connected Area) we determine the functional connectivity of wetland networks for seven migratory waterbirds with divergent habitat requirements. Analyses are performed at two spatial extents both spanning the Mediterranean Sea and centered around Greece (Balkan-Cyrenaica and Greece-Cyrenaica). We create species-specific suitable habitat maps and account for human disturbance by species-specific disturbance buffers, based on expert estimates of Flight Initiation Distances. At both spatial extents we quantitatively determine the habitat networks’ overall functional connectivity and identify wetland sites that are crucial for maintaining a well-connected network. We show that the wetland networks for both spatial extents are relatively well connected and identify several wetland sites in Greece and Libya as important for maintaining connectivity. The application of disturbance buffers results in wetland site-specific reduction of suitable habitat area (0.90–7.36%) and an overall decrease of the network’s connectivity (0.65–6.82%). In addition, we show that the habitat networks of a limited set of species can be combined into a single network which accounts for their autoecological requirements. We conclude that targeted management in few but specific wetland complexes could benefit migratory waterbird populations. Deterioration of these vital wetland sites in Greece and Libya will have disproportionate consequences to the waterbird populations they support. PMID:26258590

Analysis and Classification of Traffic in Wireless Sensor Network

DTIC Science & Technology

2007-03-01

34 1. Hurst Parameter ................................................................................35 2. Self-Similarity...traffic is self-similar, buffer size can be better designed from the forecasted traffic workload. 1. Hurst Parameter To determine the extent of self...similarity in WSN traffic, the Hurst parameter, H, is used. H also calculates the length of the long range dependence of a stochastic process. If H

Axial complex and associated structures of the sea urchin Strongylocentrotus pallidus (Sars, G.O. 1871) (Echinodermata: Echinoidea).

PubMed

Ezhova, Olga Vladimirovna; Malakhov, Vladimir Vasil'yevich; Egorova, Ekaterina Alekseevna

2018-06-01

Studies of echinoid microscopic anatomy over the last two centuries have created a number of inaccuracies and mistakes that have accumulated in the descriptions of the intricate organization of the coelomic system of Echinoidea. To clarify the situation, we reconstructed the axial complex and radial complex of the echinoid Strongylocentrotus pallidus. The water ring is located between the perivisceral coelom and the perioral coelom. The oral haemal ring lies between the coelothelia of the water-vascular, perivisceral, and perioral rings. The axial part of the axial organ communicates with the oral haemal ring in interradius CD, but the axial coelom does not form the axocoelomic perihaemal ring. The ventral intestinal haemal vessel originates from the oral haemal ring in radius A, and then branches into a network of capillaries, from which the dorsal intestinal vessel starts. The pericardial coelom envelopes the pericardial part of the axial organ, the lacunae of which communicate with the haemocoel of the body wall and with the axial part of the axial organ. The genital haemal ring and the dorsal intestinal vessel communicate with the axial organ. The genital coelom passes in the CD interradius on the side opposite to the hindgut. There is a somatocoelomic perihaemal ring, which sends a pair of coelomic outgrowths into each radius, accompanied by a radial haemal vessel in the oral part. The mistakes and inaccuracies of early descriptions of the echinoid axial complex are listed. The axial complex and associated structures of sea urchins are compared with other eleutherozoans. © 2018 Wiley Periodicals, Inc.

Hydrolysis and nucleophilic substitution of model and ultimate carcinogens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helmick, J.S.

1992-01-01

The hydrolysis reaction of the Model Carcinogen O-pivaloyl-N-(4-chlorophenyl)hydroxylamine in aqueous buffer (pH 7.0-10.0) proceeds by was of a nitrenium ion intermediate. The products formed from this process are predominately 2,4-dichloroaniline, and 2-hydroxy-4-chloro-pivalanilide. At pH 10-13 the rate becomes dependent upon hydroxide. The product that is formed is 4-chlorophenylhydroxylamine. 4-Chlorophenyl-hydroxylamine is formed by basic ester hydrolysis determined by an [sup 18]O GC-MS experiment. The reaction of O-pivaloyl-N-(4-chlorophenyl)hydroxylamine in an aqueous diethylamine (pH 11.3) buffer gave 4-chlorophenyl-N,N-diethylhydrazine as the substitution product in a 16% yield. The reaction of O-pivaloyl-N-(4-methylphenyl)hydroxylamine with diethylamine gave a 1% yield of the hydrazine product. The reaction ofmore » N,N-dimethylanline and aniline with ring-substituted O-pivaloyl-N-arylhydroxylamines in MeOH generates products of nucleophilic attack on the nitrogen of the hydroxylamine derivative. The hydrolysis of the ultimate carcinogen N-(sulfonatooxy)-N-4-aminobiphenyl proceeds by two consecutive pseudo-first-order processes and generates predominately a product of nucleophilic attack by chloride ion at the ortho position of the aromatic ring. A labile intermediate identified as N-acetypl-4-hydroxy-4-phenyl-2,5-cyclohexadienone imine has been detected by NMR. This intermediate rearranges to form 4-hydroxy-3-phenylacetanilide. The hydrolysis of N-benzoyl-4-hydroxy-4-hydroxy-4-phenyl-2,5-cyclohexadienone imine proceeds by way of two consecutive pseudo-first-order processes. The hydrolysis of N-benzoyl-4-methoxy-4-phenyl-2,5-cyclohexadienone imine also proceeds by two consecutive pseudo-first-order processes. Spectroscopic evidence of two diastereomeric intermediates formed from the hydrolysis of the N-benzoyl imines were tentatively identified as N-benzoyl-N-hydroxy-4-hydroxy-4-phenyl-2,5-cyclohexadienone imine.« less

Methanol fractionations of Catha edulis Frosk (Celastraceae) contracted Lewis rat aorta in vitro: a comparison between crimson and green leaves.

PubMed

Mahmood, Samira Abdulla; Pavlovic, Dragan; Hoffmann, Ulrich

2009-05-07

The study investigated the effect of methanol extract and its fractionations obtained from Yemeni khat on the smooth muscle isometric tension in Lewis rat aortal ring preparations and compared the effects of the crimson and green leaves. Khat leaves were sorted into green (khat Light; KL) and crimson (khat Dark; KD) leaves, extracted with methanol, followed with solvent-solvent extraction (benzene, chloroform and ethylacetate). The contractile activity of the fractions was tested using aortal ring preparations. The control (phenylepherine contraction) methanol extracts contracted aortas at concentrations 250, 125 and 67.5 microg/ml buffer by 80.2%, 57.3%, 26.4% and 81.5%, 65.6%, 24.6% for KL and KD, respectively. Fractions of benzene (BF) and ethylacetate (EaF) contracted the aorta with 2 microgm, whereas, chloroform (ChF) with 1 microgm/1 ml buffer was less potent. The shape of contraction curve produced by EaF differed from that of ChF and BF of both (KL and KD). The EaF induced-contraction peaked after 3.3 +/- 0.94 mins, whereas those of BF and CHF peaked after 18.0 +/- 2.2, 19.7 +/- 0.94 mins, respectively. Pre-incubation with nifedipine (10(-6) M) insignificantly reduced the contraction induced by all fractionations, but prazosin (10(-6) M) reduced the contraction by 81.9%, 63.1%, 71.8% with p = 0.23, 0.09, 0.15 for BF, ChF and EaF of KL, respectively. It significantly reduced contraction of ChF, 64.1%; p = 0.02, and of EaF, 73.5%; p = 0.04 of KD, while the reduction in contraction of BF was 63.1%; p = 0.06. In conclusion, fractions of green and crimson Yemeni khat leaves contracted aortas of Lewis rats. Both leaves behave almost similarly. Contraction induced by chloroform fraction produced alpha-sympathetic activity.

SPADnet: a fully digital, scalable, and networked photonic component for time-of-flight PET applications

NASA Astrophysics Data System (ADS)

Bruschini, Claudio; Charbon, Edoardo; Veerappan, Chockalingam; Braga, Leo H. C.; Massari, Nicola; Perenzoni, Matteo; Gasparini, Leonardo; Stoppa, David; Walker, Richard; Erdogan, Ahmet; Henderson, Robert K.; East, Steve; Grant, Lindsay; Játékos, Balázs; Ujhelyi, Ferenc; Erdei, Gábor; Lörincz, Emöke; André, Luc; Maingault, Laurent; Jacolin, David; Verger, L.; Gros d'Aillon, Eric; Major, Peter; Papp, Zoltan; Nemeth, Gabor

2014-05-01

The SPADnet FP7 European project is aimed at a new generation of fully digital, scalable and networked photonic components to enable large area image sensors, with primary target gamma-ray and coincidence detection in (Time-of- Flight) Positron Emission Tomography (PET). SPADnet relies on standard CMOS technology, therefore allowing for MRI compatibility. SPADnet innovates in several areas of PET systems, from optical coupling to single-photon sensor architectures, from intelligent ring networks to reconstruction algorithms. It is built around a natively digital, intelligent SPAD (Single-Photon Avalanche Diode)-based sensor device which comprises an array of 8×16 pixels, each composed of 4 mini-SiPMs with in situ time-to-digital conversion, a multi-ring network to filter, carry, and process data produced by the sensors at 2Gbps, and a 130nm CMOS process enabling mass-production of photonic modules that are optically interfaced to scintillator crystals. A few tens of sensor devices are tightly abutted on a single PCB to form a so-called sensor tile, thanks to TSV (Through Silicon Via) connections to their backside (replacing conventional wire bonding). The sensor tile is in turn interfaced to an FPGA-based PCB on its back. The resulting photonic module acts as an autonomous sensing and computing unit, individually detecting gamma photons as well as thermal and Compton events. It determines in real time basic information for each scintillation event, such as exact time of arrival, position and energy, and communicates it to its peers in the field of view. Coincidence detection does therefore occur directly in the ring itself, in a differed and distributed manner to ensure scalability. The selected true coincidence events are then collected by a snooper module, from which they are transferred to an external reconstruction computer using Gigabit Ethernet.

A Novel Capacity Analysis for Wireless Backhaul Mesh Networks

NASA Astrophysics Data System (ADS)

Chung, Tein-Yaw; Lee, Kuan-Chun; Lee, Hsiao-Chih

This paper derived a closed-form expression for inter-flow capacity of a backhaul wireless mesh network (WMN) with centralized scheduling by employing a ring-based approach. Through the definition of an interference area, we are able to accurately describe a bottleneck collision area for a WMN and calculate the upper bound of inter-flow capacity. The closed-form expression shows that the upper bound is a function of the ratio between transmission range and network radius. Simulations and numerical analysis show that our analytic solution can better estimate the inter-flow capacity of WMNs than that of previous approach.

Inferring Spatio-temporal Variations in the Risk of Extreme Precipitation in the Western United States from Tree-ring Chronologies

NASA Astrophysics Data System (ADS)

Steinschneider, S.; Ho, M.; Cook, E. R.; Lall, U.

2017-12-01

This work explores how extreme cold-season precipitation dynamics along the west coast of the United States have varied in the past under natural climate variability through an analysis of the moisture anomalies recorded by tree-ring chronologies across the coast and interior of the western U.S. Winters with high total precipitation amounts in the coastal regions are marked by a small number of extreme storms that exhibit distinct spatial patterns of precipitation across the coast and further inland. Building from this observation, this work develops a novel application of dendroclimatic evidence to explore the following questions: a) how is extreme precipitation variability expressed in a network of tree-ring chronologies; b) can this information provide insight on the space-time variability of storm tracks that cause these extreme events; and c) how can the joint variability of extreme precipitation and storm tracks be modeled to develop consistent, multi-centennial reconstructions of both? We use gridded, tree-ring based reconstructions of the summer Palmer Drought Severity Index (PDSI) extending back 500 years within the western U.S. to build and test a novel statistical framework for reconstructing the space-time variability of coastal extreme precipitation and the associated wintertime storm tracks. Within this framework, we (1) identify joint modes of variability of extreme precipitation fields and tree-ring based PDSI reconstructions; (2) relate these modes to previously identified, unique storm track patterns associated with atmospheric rivers (ARs), which are the dominant type of storm that is responsible for extreme precipitation in the region; and (3) determine latitudinal variations of landfalling ARs across the west coast and their relationship to the these joint modes. To our knowledge, this work is the first attempt to leverage information on storm track patterns stored in a network of paleoclimate proxies to improve reconstruction fidelity.

Inferring Spatio-temporal Variations in the Risk of Extreme Precipitation in the Western United States from Tree-ring Chronologies

NASA Astrophysics Data System (ADS)

Steinschneider, S.; Ho, M.; Cook, E. R.; Lall, U.

2016-12-01

This work explores how extreme cold-season precipitation dynamics along the west coast of the United States have varied in the past under natural climate variability through an analysis of the moisture anomalies recorded by tree-ring chronologies across the coast and interior of the western U.S. Winters with high total precipitation amounts in the coastal regions are marked by a small number of extreme storms that exhibit distinct spatial patterns of precipitation across the coast and further inland. Building from this observation, this work develops a novel application of dendroclimatic evidence to explore the following questions: a) how is extreme precipitation variability expressed in a network of tree-ring chronologies; b) can this information provide insight on the space-time variability of storm tracks that cause these extreme events; and c) how can the joint variability of extreme precipitation and storm tracks be modeled to develop consistent, multi-centennial reconstructions of both? We use gridded, tree-ring based reconstructions of the summer Palmer Drought Severity Index (PDSI) extending back 500 years within the western U.S. to build and test a novel statistical framework for reconstructing the space-time variability of coastal extreme precipitation and the associated wintertime storm tracks. Within this framework, we (1) identify joint modes of variability of extreme precipitation fields and tree-ring based PDSI reconstructions; (2) relate these modes to previously identified, unique storm track patterns associated with atmospheric rivers (ARs), which are the dominant type of storm that is responsible for extreme precipitation in the region; and (3) determine latitudinal variations of landfalling ARs across the west coast and their relationship to the these joint modes. To our knowledge, this work is the first attempt to leverage information on storm track patterns stored in a network of paleoclimate proxies to improve reconstruction fidelity.

Experimental evidence for the effect of habitat loss on the dynamics of migratory networks.

PubMed

Betini, Gustavo S; Fitzpatrick, Mark J; Norris, D Ryan

2015-06-01

Migratory animals present a unique challenge for understanding the consequences of habitat loss on population dynamics because individuals are typically distributed over a series of interconnected breeding and non-breeding sites (termed migratory network). Using replicated breeding and non-breeding populations of Drosophila melanogaster and a mathematical model, we investigated three hypotheses to explain how habitat loss influenced the dynamics of populations in networks with different degrees of connectivity between breeding and non-breeding seasons. We found that habitat loss increased the degree of connectivity in the network and influenced population size at sites that were not directly connected to the site where habitat loss occurred. However, connected networks only buffered global population declines at high levels of habitat loss. Our results demonstrate why knowledge of the patterns of connectivity across a species range is critical for predicting the effects of environmental change and provide empirical evidence for why connected migratory networks are commonly found in nature. © 2015 John Wiley & Sons Ltd/CNRS.

Social Network Characteristics Moderate the Association Between Stigmatizing Attributions About HIV and Non-adherence Among Black Americans Living with HIV: a Longitudinal Assessment.

PubMed

Bogart, Laura M; Wagner, Glenn J; Green, Harold D; Mutchler, Matt G; Klein, David J; McDavitt, Bryce

2015-12-01

Stigma may contribute to HIV-related disparities among HIV-positive Black Americans. We examined whether social network characteristics moderate stigma's effects. At baseline and 6 months post-baseline, 147 HIV-positive Black Americans on antiretroviral treatment completed egocentric social network assessments, from which we derived a structural social support capacity measure (i.e., ability to leverage support from the network, represented by the average interaction frequency between the participant and each alter). Stigma was operationalized with an indicator of whether any social network member had expressed stigmatizing attributions of blame or responsibility about HIV. Daily medication adherence was monitored electronically. In a multivariate regression, baseline stigma was significantly related to decreased adherence over time. The association between stigma and non-adherence was attenuated among participants who increased the frequency of their interactions with alters over time. Well-connected social networks have the potential to buffer the effects of stigma.

Facebook and romantic relationships: intimacy and couple satisfaction associated with online social network use.

PubMed

Hand, Matthew M; Thomas, Donna; Buboltz, Walter C; Deemer, Eric D; Buyanjargal, Munkhsanaa

2013-01-01

Online social networks, such as Facebook, have gained immense popularity and potentially affect the way people build and maintain interpersonal relationships. The present study sought to examine time spent on online social networks, as it relates to intimacy and relationship satisfaction experienced in romantic relationships. Results did not find relationships between an individual's usage of online social networks and his/her perception of relationship satisfaction and intimacy. However, the study found a negative relationship between intimacy and the perception of a romantic partner's use of online social networks. This finding may allude to an attributional bias in which individuals are more likely to perceive a partner's usage as negative compared to their own usage. Additionally, it was found that intimacy mediates the relationship between online social network usage and overall relationship satisfaction, which suggests that the level of intimacy experienced in a relationship may serve as a buffer that protects the overall level of satisfaction.

Crystal structure of N-{[3-bromo-1-(phenyl-sulfon-yl)-1H-indol-2-yl]meth-yl}benzene-sulfonamide.

PubMed

Umadevi, M; Raju, P; Yamuna, R; Mohanakrishnan, A K; Chakkaravarthi, G

2015-10-01

In the title compound, C21H17BrN2O4S2, the indole ring system subtends dihedral angles of 85.96 (13) and 9.62 (16)° with the planes of the N- and C-bonded benzene rings, respectively. The dihedral angles between the benzene rings is 88.05 (17)°. The mol-ecular conformation is stabilized by intra-molecular N-H⋯O and C-H⋯O hydrogen bonds and an aromatic π-π stacking [centroid-to-centroid distance = 3.503 (2) Å] inter-action. In the crystal, short Br⋯O [2.9888 (18) Å] contacts link the mol-ecules into [010] chains. The chains are cross-linked by weak C-H⋯π inter-actions, forming a three-dimensional network.

Two-dimensional network of atomtronic qubits

NASA Astrophysics Data System (ADS)

Safaei, S.; Grémaud, B.; Dumke, R.; Kwek, L.-C.; Amico, L.; Miniatura, C.

2018-04-01

Through a combination of laser beams, we engineer a two-dimensional optical lattice of Mexican hat potentials able to host atoms in its ring-shaped wells. When tunneling can be ignored (at high laser intensities), we show that a well-defined qubit can be associated with the states of the atoms trapped in each of the rings. Each of these two-level systems can be manipulated by a suitable configuration of Raman laser beams imprinting a synthetic flux onto each Mexican hat cell of the lattice. Overall, we believe that the system has the potential to form a scalable architecture for atomtronic flux qubits.

1-(2-Hy­droxy­eth­yl)-3-[(2-hy­droxy­eth­yl)amino]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione

PubMed Central

Xie, Zhi-Xiong; Zhao, Sheng-Yin

2011-01-01

There are four molecules in the asymmetric unit of the title compound, C16H17N3O4, in which the dihedral angles between the indole ring system and maleimide ring are 4.5 (3), 8.3 (3), 8.4 (2) and 10.4 (2)°. In the crystal, mol­ecules are linked by numerous N—H⋯O and O—H⋯O hydrogen bonds, generating a three-dimensional network. PMID:21754135

1,3-Bis[(5-amino-furan-2-yl)meth-yl]-3,4,5,6-tetra-hydro-pyrimidin-1-ium hexa-fluoro-phosphate.

PubMed

Akkurt, Mehmet; Akkoç, Senem; Gök, Yetkin; Tahir, Muhammad Nawaz

2013-01-01

The asymmetric unit of the title salt, C16H21N2O2 (+)·PF6 (-), contains half of the whole ion pair, which has crystallographic mirror symmetry. Two F atoms related by the mirror plane are disordered over two sites of equal occupancy. The dihedral angle between the central ring and the furan ring is 59.3 ()°. In the crystal, the anions and cations are linked through C-H⋯F inter-actions, forming a three-dimensional network.

5-Chloro-2-nitro-phenol.

PubMed

Ren, Dong-Mei

2012-05-01

The asymmetric unit of the title compound, C(6)H(4)ClNO(3), contains two independent mol-ecules in which the dihedral angles between the benzene ring and the nitro groups are 2.5 (1) and 8.5 (1)°. Intra-molecular O-H⋯O hydrogen bonds involving the hy-droxy and nitro substituents result in the formation of S(6) six-membered rings. In the crystal, O-H⋯O, O-H⋯Cl and C-H⋯O hydrogen bonds together with Cl⋯O contacts [3.238 (3) and 3.207 (3) Å] generate a three-dimensional network.

From Data to Equations: Inferring the Laws governing Saturn's Ring Temperature

NASA Astrophysics Data System (ADS)

Altobelli, N.; Lopez-Paz, D.; Spilker, L.; Pilorz, S.

2011-10-01

Six years after Saturn Orbit Insertion (SOI), the Composite Infrared Spectrometer (CIRS) on-board the Cassini Spacecraft has been performing a thermal mapping of Saturn's main rings, by measuring the thermal radiance in the far-infrared ( [10-600] cm-1 ) for different viewing geometries. So far, more than 2.5 millions individual spectra have been recorded, from Saturn's northern winter solstice till Saturn's northern spring. We present a first attempt of treating the data set globally by applying numerical data mining techniques inherited from the field of artificial intelligence, such as neural networks and genetic programing.

2-(Maleimidomethyl)-1,3-Dioxanes (MD): a Serum-Stable Self-hydrolysable Hydrophilic Alternative to Classical Maleimide Conjugation

NASA Astrophysics Data System (ADS)

Dovgan, Igor; Kolodych, Sergii; Koniev, Oleksandr; Wagner, Alain

2016-08-01

The vast majority of antibody-drug conjugates (ADC) are prepared through amine-to-thiol conjugation. To date, N-Succinimidyl-4-(maleimidomethyl) cyclohexanecarboxylate (SMCC) has been one of the most frequently applied reagents for the preparation of ADC and other functional conjugates. However, SMCC-based conjugates suffer from limited stability in blood circulation and from a hydrophobic character of the linker, which may give rise to major pharmacokinetic implications. To address this issue, we have developed a heterobifunctional analogue of a SMCC reagent, i.e., sodium 4-(maleimidomethyl)-1,3-dioxane-5-carbonyl)oxy)-2,3,5,6- tetrafluorobenzenesulfonate (MDTF) for amine-to-thiol conjugation. By replacing the cyclohexyl ring in the SMCC structure with the 1,3-dioxane, we increased the hydrophilicity of the linker. A FRET probe based on MD linker was prepared and showed superior stability compared to the MCC linker in human plasma, as well as in a variety of aqueous buffers. A detailed investigation demonstrated an accelerated succinimide ring opening for MD linker, resulting in stabilized conjugates. Finally, the MDTF reagent was applied for the preparation of serum stable antibody-dye conjugate.

Porous Teflon ring-solid disk electrode arrangement for differential mass spectrometry measurements in the presence of convective flow generated by a jet impinging electrode in the wall-jet configuration.

PubMed

Treufeld, Imre; Jebaraj, Adriel Jebin Jacob; Xu, Jing; Martins de Godoi, Denis; Scherson, Daniel

2012-06-19

A porous Teflon ring|solid disk electrode is herein described specifically designed for acquiring online mass spectrometric measurements under well-defined forced convection created by liquid emerging from a circular nozzle impinging on the disk under wall-jet conditions. Measurements were performed for the oxidation of hydrazine, N(2)H(4), in a deaerated phosphate buffer electrolyte (pH 7) on Au, a process known to yield dinitrogen as the product. The N(2)(+) ion currents, measured by the mass spectrometer, i(N(2)(+)), as well as the corresponding polarization curves recorded simultaneously displayed very similar s-like shapes when plotted as a function of the potential applied to the Au disk. In fact, the limiting currents observed both electrochemically and spectrometrically were found to be proportional to [N(2)H(4)]. However, the limiting values of i(N(2)(+)) did not increase monotonically with the flow rate, ν(f), reaching instead a maximum and then decreasing to values independent of ν(f). This behavior has been attributed in part to hindrances in the mass transport of gases through the porous materials.

Packet-aware transport for video distribution [Invited

NASA Astrophysics Data System (ADS)

Aguirre-Torres, Luis; Rosenfeld, Gady; Bruckman, Leon; O'Connor, Mannix

2006-05-01

We describe a solution based on resilient packet rings (RPR) for the distribution of broadcast video and video-on-demand (VoD) content over a packet-aware transport network. The proposed solution is based on our experience in the design and deployment of nationwide Triple Play networks and relies on technologies such as RPR, multiprotocol label switching (MPLS), and virtual private LAN service (VPLS) to provide the most efficient solution in terms of utilization, scalability, and availability.

Modeling of the Space Station Freedom data management system

NASA Technical Reports Server (NTRS)

Johnson, Marjory J.

1990-01-01

The Data Management System (DMS) is the information and communications system onboard Space Station Freedom (SSF). Extensive modeling of the DMS is being conducted throughout NASA to aid in the design and development of this vital system. Activities discussed at NASA Ames Research Center to model the DMS network infrastructure are discussed with focus on the modeling of the Fiber Distributed Data Interface (FDDI) token-ring protocol and experimental testbedding of networking aspects of the DMS.

A Deep Space Network Portable Radio Science Receiver

NASA Technical Reports Server (NTRS)

Jongeling, Andre P.; Sigman, Elliott H.; Chandra, Kumar; Trinh, Joseph T.; Navarro, Robert; Rogstad, Stephen P.; Goodhart, Charles E.; Proctor, Robert C.; Finley, Susan G.; White, Leslie A.

2009-01-01

The Radio Science Receiver (RSR) is an open-loop receiver installed in NASA s Deep Space Network (DSN), which digitally filters and records intermediate-frequency (IF) analog signals. The RSR is an important tool for the Cassini Project, which uses it to measure perturbations of the radio-frequency wave as it travels between the spacecraft and the ground stations, allowing highly detailed study of the composition of the rings, atmosphere, and surface of Saturn and its satellites.

The Buffer Diagnostic Prototype: A fault isolation application using CLIPS

NASA Technical Reports Server (NTRS)

Porter, Ken

1994-01-01

This paper describes problem domain characteristics and development experiences from using CLIPS 6.0 in a proof-of-concept troubleshooting application called the Buffer Diagnostic Prototype. The problem domain is a large digital communications subsystems called the real-time network (RTN), which was designed to upgrade the launch processing system used for shuttle support at KSC. The RTN enables up to 255 computers to share 50,000 data points with millisecond response times. The RTN's extensive built-in test capability but lack of any automatic fault isolation capability presents a unique opportunity for a diagnostic expert system application. The Buffer Diagnostic Prototype addresses RTN diagnosis with a multiple strategy approach. A novel technique called 'faulty causality' employs inexact qualitative models to process test results. Experimental knowledge provides a capability to recognize symptom-fault associations. The implementation utilizes rule-based and procedural programming techniques, including a goal-directed control structure and simple text-based generic user interface that may be reusable for other rapid prototyping applications. Although limited in scope, this project demonstrates a diagnostic approach that may be adapted to troubleshoot a broad range of equipment.

Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers

PubMed Central

Gurven, Michael; Jaeggi, Adrian V.; von Rueden, Chris; Hooper, Paul L.; Kaplan, Hillard

2015-01-01

Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital. PMID:26526638

Friendly-Sharing: Improving the Performance of City Sensoring through Contact-Based Messaging Applications.

PubMed

Herrera-Tapia, Jorge; Hernández-Orallo, Enrique; Tomás, Andrés; Manzoni, Pietro; Tavares Calafate, Carlos; Cano, Juan-Carlos

2016-09-18

Regular citizens equipped with smart devices are being increasingly used as "sensors" by Smart Cities applications. Using contacts among users, data in the form of messages is obtained and shared. Contact-based messaging applications are based on establishing a short-range communication directly between mobile devices, and on storing the messages in these devices for subsequent delivery to cloud-based services. An effective way to increase the number of messages that can be shared is to increase the contact duration. We thus introduce the Friendly-Sharing diffusion approach, where, during a contact, the users are aware of the time needed to interchange the messages stored in their buffers, and they can thus decide to wait more time in order to increase the message sharing probability. The performance of this approach is anyway closely related to the size of the buffer in the device. We therefore compare various policies either for the message selection at forwarding times and for message dropping when the buffer is full. We evaluate our proposal with a modified version of the Opportunistic Networking Environment (ONE) simulator and using real human mobility traces.

Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers.

PubMed

Gurven, Michael; Jaeggi, Adrian V; von Rueden, Chris; Hooper, Paul L; Kaplan, Hillard

2015-08-01

Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital.

Simplified transient isotachophoresis/capillary gel electrophoresis method for highly sensitive analysis of polymerase chain reaction samples on a microchip with laser-induced fluorescence detection.

PubMed

Liu, Dayu; Ou, Ziyou; Xu, Mingfei; Wang, Lihui

2008-12-19

We present a sensitive, simple and robust on-chip transient isotachophoresis/capillary gel electrophoresis (tITP/CGE) method for the analysis of polymerase chain reaction (PCR) samples. Using chloride ions in the PCR buffer and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) in the background electrolyte, respectively, as the leading and terminating electrolytes, the tITP preconcentration was coupled with CGE separation with double-T shaped channel network. The tITP/CGE separation was carried out with a single running buffer. The separation process involved only two steps that were performed continuously with the sequential switching of four voltage outputs. The tITP/CGE method showed an analysis time and a separation efficiency comparable to those of standard CGE, while the signal intensity was enhanced by factors of over 20. The limit of detection of the chip-based tITP/CGE method was estimated to be 1.1 ng/mL of DNA in 1x PCR buffer using confocal fluorescence detection following 473 nm laser excitation.

Using minimal spanning trees to compare the reliability of network topologies

NASA Technical Reports Server (NTRS)

Leister, Karen J.; White, Allan L.; Hayhurst, Kelly J.

1990-01-01

Graph theoretic methods are applied to compute the reliability for several types of networks of moderate size. The graph theory methods used are minimal spanning trees for networks with bi-directional links and the related concept of strongly connected directed graphs for networks with uni-directional links. A comparison is conducted of ring networks and braided networks. The case is covered where just the links fail and the case where both links and nodes fail. Two different failure modes for the links are considered. For one failure mode, the link no longer carries messages. For the other failure mode, the link delivers incorrect messages. There is a description and comparison of link-redundancy versus path-redundancy as methods to achieve reliability. All the computations are carried out by means of a fault tree program.

A pixel read-out architecture implementing a two-stage token ring, zero suppression and compression

NASA Astrophysics Data System (ADS)

Heuvelmans, S.; Boerrigter, M.

2011-01-01

Increasing luminosity in high energy physics experiments leads to new challenges in the design of data acquisition systems for pixel detectors. With the upgrade of the LHCb experiment, the data processing will be changed; hit data from every collision will be transported off the pixel chip, without any trigger selection. A read-out architecture is proposed which is able to obtain low hit data loss on limited silicon area by using the logic beneath the pixels as a data buffer. Zero suppression and redundancy reduction ensure that the data rate off chip is minimized. A C++ model has been created for simulation of functionality and data loss, and for system development. A VHDL implementation has been derived from this model.

Building Social Support Systems through a Babysitting Exchange Program.

ERIC Educational Resources Information Center

Douglas, Jeanne A.; Jason, Leonard A.

A babysitting exchange program was created for a group of women in order to build a social support network and to provide a test of the buffer hypothesis (i.e., the idea that social support may shield an individual from the negative physical and mental consequences of stress, particularly when stress is at high levels). The sample consisted of 30…

Analog hardware for delta-backpropagation neural networks

NASA Technical Reports Server (NTRS)

Eberhardt, Silvio P. (Inventor)

1992-01-01

This is a fully parallel analog backpropagation learning processor which comprises a plurality of programmable resistive memory elements serving as synapse connections whose values can be weighted during learning with buffer amplifiers, summing circuits, and sample-and-hold circuits arranged in a plurality of neuron layers in accordance with delta-backpropagation algorithms modified so as to control weight changes due to circuit drift.

Transition state analogue imprinted polymers as artificial amidases for amino acid p-nitroanilides: morphological effects of polymer network on catalytic efficiency.

PubMed

Mathew, Divya; Thomas, Benny; Devaky, K S

2017-11-13

The morphology of the polymer network - porous/less porous - plays predominant role in the amidase activities of the polymer catalysts in the hydrolytic reactions of amino acid p-nitroanilides. Polymers with the imprints of stable phosphonate analogue of the intermediate of hydrolytic reactions were synthesized as enzyme mimics. Molecular imprinting was carried out in thermodynamically stable porogen dimethyl sulphoxide and unstable porogen chloroform, to investigate the morphological effects of polymers on catalytic amidolysis. It was found that the medium of polymerization has vital influence in the amidase activities of the enzyme mimics. The morphological studies of the polymer catalysts were carried out by scanning electron microscopy and Bruner-Emmett-Teller analysis. The morphology of the polymer catalysts and their amidase activities are found to be dependent on the composition of reaction medium. The polymer catalyst prepared in dimethyl sulphoxide is observed to be efficient in 1:9 acetonitrile (ACN)-Tris HCl buffer and that prepared in chloroform is noticed to be stereo specifically and shape-selectively effective in 9:1 ACN-Tris HCl buffer. The solvent memory effect in catalytic amidolysis was investigated using the polymer prepared in acetonitrile.

High-performance parallel interface to synchronous optical network gateway

DOEpatents

St. John, Wallace B.; DuBois, David H.

1996-01-01

A system of sending and receiving gateways interconnects high speed data interfaces, e.g., HIPPI interfaces, through fiber optic links, e.g., a SONET network. An electronic stripe distributor distributes bytes of data from a first interface at the sending gateway onto parallel fiber optics of the fiber optic link to form transmitted data. An electronic stripe collector receives the transmitted data on the parallel fiber optics and reforms the data into a format effective for input to a second interface at the receiving gateway. Preferably, an error correcting syndrome is constructed at the sending gateway and sent with a data frame so that transmission errors can be detected and corrected in a real-time basis. Since the high speed data interface operates faster than any of the fiber optic links the transmission rate must be adapted to match the available number of fiber optic links so the sending and receiving gateways monitor the availability of fiber links and adjust the data throughput accordingly. In another aspect, the receiving gateway must have sufficient available buffer capacity to accept an incoming data frame. A credit-based flow control system provides for continuously updating the sending gateway on the available buffer capacity at the receiving gateway.

Social contact patterns can buffer costs of forgetting in the evolution of cooperation.

PubMed

Stevens, Jeffrey R; Woike, Jan K; Schooler, Lael J; Lindner, Stefan; Pachur, Thorsten

2018-06-13

Analyses of the evolution of cooperation often rely on two simplifying assumptions: (i) individuals interact equally frequently with all social network members and (ii) they accurately remember each partner's past cooperation or defection. Here, we examine how more realistic, skewed patterns of contact-in which individuals interact primarily with only a subset of their network's members-influence cooperation. In addition, we test whether skewed contact patterns can counteract the decrease in cooperation caused by memory errors (i.e. forgetting). Finally, we compare two types of memory error that vary in whether forgotten interactions are replaced with random actions or with actions from previous encounters. We use evolutionary simulations of repeated prisoner's dilemma games that vary agents' contact patterns, forgetting rates and types of memory error. We find that highly skewed contact patterns foster cooperation and also buffer the detrimental effects of forgetting. The type of memory error used also influences cooperation rates. Our findings reveal previously neglected but important roles of contact pattern, type of memory error and the interaction of contact pattern and memory on cooperation. Although cognitive limitations may constrain the evolution of cooperation, social contact patterns can counteract some of these constraints. © 2018 The Author(s).

Crystal structure of 3-[(4-benzyl-piperazin-1-yl)meth-yl]-5-(thio-phen-2-yl)-2,3-di-hydro-1,3,4-oxa-diazole-2-thione.

PubMed

Al-Omary, Fatmah A M; El-Emam, Ali A; Ghabbour, Hazem A; Chidan Kumar, C S; Quah, Ching Kheng; Fun, Hoong-Kun

2015-03-01

The title 1,3,4-oxa-diazole-2-thione derivative, C18H20N4OS2, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. The 2-thienyl rings in both mol-ecules are rotationally disordered over two orientations by approximately 180° about the single C-C bond that connects it to the oxa-diazole thione ring; the ratios of site occupancies for the major and minor components were fixed in the structure refinement at 0.8:0.2 and 0.9:0.1 in mol-ecules A and B, respectively. The 1,3,4-oxa-diazole-2-thione ring forms dihedral angles of 7.71 (16), 10.0 (11) and 77.50 (12)° (mol-ecule A), and 6.5 (3), 6.0 (9) and 55.30 (12)° (mol-ecule B) with the major and minor parts of the disordered thio-phene ring and the mean plane of the adjacent piperazine ring, respectively, resulting in approximately V-shaped conformations for the mol-ecules. The piperazine ring in both mol-ecules adopts a chair conformation. The terminal benzene ring is inclined towards the mean plane of the piperazine ring with N-C-C-C torsion angles of -58.2 (3) and -66.2 (3)° in mol-ecules A and B, respectively. In the crystal, no inter-molecular hydrogen bonds are observed. The crystal packing features short S⋯S contacts [3.4792 (9) Å] and π-π inter-actions [3.661 (3), 3.664 (11) and 3.5727 (10) Å], producing a three-dimensional network.

Pooled versus separate tree-ring δD measurements, and implications for reconstruction of the Arctic Oscillation in northwestern China.

PubMed

Liu, Xiaohong; An, Wenling; Treydte, Kerstin; Wang, Wenzhi; Xu, Guobao; Zeng, Xiaomin; Wu, Guoju; Wang, Bo; Zhang, Xuanwen

2015-04-01

Stable hydrogen isotope ratios (δD) in tree rings are an attractive but still rarely explored terrestrial archive of past climatic information. Because the preparation of the cellulose nitrate for δD measurements requires more wood and a longer preparation time than preparation techniques for other isotopes in cellulose (δ18O or δ13C), it is challenging to obtain high-resolution records, especially for slow-growing trees at high elevations and in boreal regions. Here, we tested whether annually pooled samples of Qinghai spruce (Picea crassifolia Kom.) trees from northwestern China provided results similar to those derived as the mean of individual measurements of the same trees and whether the resulting chronologies recorded useful climate information. Inter-tree variability of δD was higher than that of measured ring width for the same trees. We found higher and significant coherence between pooled and mean isotope chronologies than that among the individual series. It showed a logarithmic relationship between ring mass and δD; however, accounting for the influence of ring mass on δD values only slightly improved the strength of climatic signals in the pooled records. Tree-ring δD was significantly positively correlated with the mean, maximum, and minimum temperatures during the previous winter and with maximum temperature during the current August, and significantly negatively correlated with precipitation in the previous November to January and the current July. The winter climate signal seems to dominate tree-ring δD through the influence of large-scale atmospheric circulation patterns, i.e. the Arctic Oscillation. These results will facilitate reconstruction of winter atmospheric circulation patterns over northwestern China based on a regional tree-ring δD networks. Copyright © 2015 Elsevier B.V. All rights reserved.

Boroxol rings from diffraction data on vitreous boron trioxide.

PubMed

Soper, Alan K

2011-09-14

There has been a considerable debate about the nature of the short range atomic order in vitreous B(2)O(3). Some authorities state that it is not possible to build a model of glassy boron oxide of the correct density containing a large number of six-membered rings which also fits experimental diffraction data, but recent computer simulations appear to overrule that view. To discover which view is correct I use empirical potential structure refinement (EPSR) on existing neutron and x-ray diffraction data to build two models of vitreous B(2)O(3). One of these consists only of single boron and oxygen atoms arranged in a network to reproduce the diffraction data as closely as possible. This model has less than 10% of boron atoms in boroxol rings. The second model is made up of an equimolar mixture of B(3)O(3) hexagonal ring 'molecules' and BO(3) triangular molecules, with no free boron or oxygen atoms. This second model therefore has 75% of the boron atoms in boroxol rings. It is found that both models give closely similar diffraction patterns, suggesting that the diffraction data in this case are not sensitive to the number of boroxol rings present in the structure. This reinforces recent Raman, ab initio, and NMR claims that the percentage of boroxol rings in this material may be as high as 75%. The findings of this study probably explain why some interpretations based on different simulation techniques only find a small fraction of boroxol rings. The results also highlight the power of EPSR for the extraction of accurate atomistic representations of amorphous structures, provided adequate additional, non-scattering data (such as Raman and NMR in this case) are available.

Design of a Multicast Optical Packet Switch Based on Fiber Bragg Grating Technology for Future Networks

NASA Astrophysics Data System (ADS)

Cheng, Yuh-Jiuh; Yeh, Tzuoh-Chyau; Cheng, Shyr-Yuan

2011-09-01

In this paper, a non-blocking multicast optical packet switch based on fiber Bragg grating technology with optical output buffers is proposed. Only the header of optical packets is converted to electronic signals to control the fiber Bragg grating array of input ports and the packet payloads should be transparently destined to their output ports so that the proposed switch can reduce electronic interfaces as well as the bit rate. The modulation and the format of packet payloads may be non-standard where packet payloads could also include different wavelengths for increasing the volume of traffic. The advantage is obvious: the proposed switch could transport various types of traffic. An easily implemented architecture which can provide multicast services is also presented. An optical output buffer is designed to queue the packets if more than one incoming packet should reach to the same destination output port or including any waiting packets in optical output buffer that will be sent to the output port at a time slot. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The fiber Bragg grating arrays for both input ports and output ports are designed for routing incoming packets using optical code division multiple access technology.

Three-dimensional carbon allotropes comprising phenyl rings and acetylenic chains in sp+ sp 2 hybrid networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jian -Tao; Chen, Changfeng; Li, Han -Dong

Here, we here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+ sp 2 bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp 2-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells R - 3m symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicatemore » that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.« less

Three-dimensional carbon allotropes comprising phenyl rings and acetylenic chains in sp+ sp 2 hybrid networks

DOE PAGES

Wang, Jian -Tao; Chen, Changfeng; Li, Han -Dong; ...

2016-04-18

Here, we here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+ sp 2 bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp 2-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells R - 3m symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicatemore » that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.« less

Photon hopping and nanowire based hybrid plasmonic waveguide and ring-resonator

PubMed Central

Gu, Zhiyuan; Liu, Shuai; Sun, Shang; Wang, Kaiyang; Lyu, Quan; Xiao, Shumin; Song, Qinghai

2015-01-01

Nanowire based hybrid plasmonic structure plays an important role in achieving nanodevices, especially for the wide band-gap materials. However, the conventional schemes of nanowire based devices such as nano-resonators are usually isolated from the integrated nano-network and have extremely low quality (Q) factors. Here we demonstrate the transmission of waves across a gap in hybrid plasmonic waveguide, which is termed as “photon hopping”. Based on the photon hopping, we show that the emissions from nanodevices can be efficiently collected and conducted by additional nanowires. The collection ratio can be higher than 50% for a wide range of separation distance, transverse shift, and tilt. Moreover, we have also explored the possibility of improving performances of individual devices by nano-manipulating the nanowire to a pseudo-ring. Our calculations show that both Q factor and Purcell factor have been increased by more than an order of magnitude. We believe that our researches will be essential to forming nanolasers and the following nano-networks.

Teloplasm formation in a leech, Helobdella triserialis, is a microtubule-dependent process.

PubMed

Astrow, S H; Holton, B; Weisblat, D A

1989-10-01

Fertilized eggs of the leech Helobdella triserialis undergo a cytoplasmic reorganization which generates domains of nonyolky cytoplasm, called teloplasm, at the animal and vegetal poles. The segregation of teloplasm to one cell of the eight-cell embryo is responsible for a unique developmental fate of that cell, i.e., to give rise to segmental ectoderm and mesoderm. We have studied the cytoplasmic movements that generate teloplasm using time-lapse video microscopy; the formation and migration of rings of nonyolky cytoplasm were visualized using transmitted light, while the movements of mitochondria into these rings were monitored with epifluorescence after labeling embryos with rhodamine 123, a fluorescent mitochondrial dye. To examine the likelihood that cytoskeletal elements play a role in the mechanism of teloplasm formation in Helobdella, we examined the distribution of microtubules and microfilaments during the first cell cycle by indirect immunofluorescence and rhodamine-phalloidin labeling, respectively. The cortex of the early embryo contained a network of microtubules many of which were oriented parallel to the cell surface. As teloplasm formation ensued, microtubule networks became concentrated in the animal and the vegetal cortex relative to the equatorial cortex. More extensive microtubule arrays were found within the rings of teloplasm. Actin filaments appeared in the form of narrow rings in the cortex, but these varied apparently randomly from embryo to embryo in terms of number, size, and position. The role of microtubules and microfilaments in teloplasm formation was tested using depolymerizing agents. Teloplasm formation was blocked by microtubule inhibitors, but not by microfilament inhibitors. These results differ significantly from those obtained in embryos of the oligochaete Tubifex hattai, suggesting that the presumably homologous cytoplasmic reorganizations seen in these two annelids have different cytoskeletal dependencies.

Automated sample-changing robot for solution scattering experiments at the EMBL Hamburg SAXS station X33

PubMed Central

Round, A. R.; Franke, D.; Moritz, S.; Huchler, R.; Fritsche, M.; Malthan, D.; Klaering, R.; Svergun, D. I.; Roessle, M.

2008-01-01

There is a rapidly increasing interest in the use of synchrotron small-angle X-ray scattering (SAXS) for large-scale studies of biological macromolecules in solution, and this requires an adequate means of automating the experiment. A prototype has been developed of an automated sample changer for solution SAXS, where the solutions are kept in thermostatically controlled well plates allowing for operation with up to 192 samples. The measuring protocol involves controlled loading of protein solutions and matching buffers, followed by cleaning and drying of the cell between measurements. The system was installed and tested at the X33 beamline of the EMBL, at the storage ring DORIS-III (DESY, Hamburg), where it was used by over 50 external groups during 2007. At X33, a throughput of approximately 12 samples per hour, with a failure rate of sample loading of less than 0.5%, was observed. The feedback from users indicates that the ease of use and reliability of the user operation at the beamline were greatly improved compared with the manual filling mode. The changer is controlled by a client–server-based network protocol, locally and remotely. During the testing phase, the changer was operated in an attended mode to assess its reliability and convenience. Full integration with the beamline control software, allowing for automated data collection of all samples loaded into the machine with remote control from the user, is presently being implemented. The approach reported is not limited to synchrotron-based SAXS but can also be used on laboratory and neutron sources. PMID:25484841

First Test Of A New High Resolution Positron Camera With Four Area Detectors

NASA Astrophysics Data System (ADS)

van Laethem, E.; Kuijk, M.; Deconinck, Frank; van Miert, M.; Defrise, Michel; Townsend, D.; Wensveen, M.

1989-10-01

A PET camera consisting of two pairs of parallel area detectors has been installed at the cyclotron unit of VUB. The detectors are High Density Avalanche Chambers (HIDAC) wire-chambers with a stack of 4 or 6 lead gamma-electron converters, the sensitive area being 30 by 30 cm. The detectors are mounted on a commercial gantry allowing a 180 degree rotation during acquisition, as needed for a fully 3D image reconstruction. The camera has been interfaced to a token-ring computer network consisting of 5 workstations among which the various tasks (acquisition, reconstruction, display) can be distributed. Each coincident event is coded in 48 bits and is transmitted to the computer bus via a 512 kbytes dual ported buffer memory allowing data rates of up to 50 kHz. Fully 3D image reconstruction software has been developed, and includes new reconstruction algorithms allowing a better utilization of the available projection data. Preliminary measurements and imaging of phantoms and small animals (with 18FDG) have been performed with two of the four detectors mounted on the gantry. They indicate the expected 3D isotropic spatial resolution of 3.5 mm (FWHM, line source in air) and a sensitivity of 4 cps/μCi for a centred point source in air, corresponding to typical data rates of a few kHz. This latter figure is expected to improve by a factor of 4 after coupling of the second detector pair, since the coincidence sensitivity of this second detector pair is a factor 3 higher than that of the first one.

Structural and kinetic analysis of the COP9-Signalosome activation and the cullin-RING ubiquitin ligase deneddylation cycle

PubMed Central

Mosadeghi, Ruzbeh; Reichermeier, Kurt M; Winkler, Martin; Schreiber, Anne; Reitsma, Justin M; Zhang, Yaru; Stengel, Florian; Cao, Junyue; Kim, Minsoo; Sweredoski, Michael J; Hess, Sonja; Leitner, Alexander; Aebersold, Ruedi; Peter, Matthias; Deshaies, Raymond J; Enchev, Radoslav I

2016-01-01

The COP9-Signalosome (CSN) regulates cullin–RING ubiquitin ligase (CRL) activity and assembly by cleaving Nedd8 from cullins. Free CSN is autoinhibited, and it remains unclear how it becomes activated. We combine structural and kinetic analyses to identify mechanisms that contribute to CSN activation and Nedd8 deconjugation. Both CSN and neddylated substrate undergo large conformational changes upon binding, with important roles played by the N-terminal domains of Csn2 and Csn4 and the RING domain of Rbx1 in enabling formation of a high affinity, fully active complex. The RING domain is crucial for deneddylation, and works in part through conformational changes involving insert-2 of Csn6. Nedd8 deconjugation and re-engagement of the active site zinc by the autoinhibitory Csn5 glutamate-104 diminish affinity for Cul1/Rbx1 by ~100-fold, resulting in its rapid ejection from the active site. Together, these mechanisms enable a dynamic deneddylation-disassembly cycle that promotes rapid remodeling of the cellular CRL network. DOI: http://dx.doi.org/10.7554/eLife.12102.001 PMID:27031283

Value-Range Analysis of C Programs

NASA Astrophysics Data System (ADS)

Simon, Axel

In 1988, Robert T. Morris exploited a so-called buffer-overflow bug in finger (a dæmon whose job it is to return information on local users) to mount a denial-of-service attack on hundreds of VAX and Sun-3 computers [159]. He created what is nowadays called a worm; that is, a crafted stream of bytes that, when sent to a computer over the network, utilises a buffer-overflow bug in the software of that computer to execute code encoded in the byte stream. In the case of a worm, this code will send the very same byte stream to other computers on the network, thereby creating an avalanche of network traffic that ultimately renders the network and all computers involved in replicating the worm inaccessible. Besides duplicating themselves, worms can alter data on the host that they are running on. The most famous example in recent years was the MSBlaster32 worm, which altered the configuration database on many Microsoft Windows machines, thereby forcing the computers to reboot incessantly. Although this worm was rather benign, it caused huge damage to businesses who were unable to use their IT infrastructure for hours or even days after the appearance of the worm. A more malicious worm is certainly conceivable [187] due to the fact that worms are executed as part of a dæmon (also known as "service" on Windows machines) and thereby run at a privileged level, allowing access to any data stored on the remote computer. While the deletion of data presents a looming threat to valuable information, even more serious uses are espionage and theft, in particular because worms do not have to affect the running system and hence may be impossible to detect.

Mobile Transactional Modelling: From Concepts to Incremental Knowledge

NASA Astrophysics Data System (ADS)

Launders, Ivan; Polovina, Simon; Hill, Richard

In 1988, Robert T. Morris exploited a so-called buffer-overflow bug in finger (a dæmon whose job it is to return information on local users) to mount a denial-of-service attack on hundreds of VAX and Sun-3 computers [159]. He created what is nowadays called a worm; that is, a crafted stream of bytes that, when sent to a computer over the network, utilises a buffer-overflow bug in the software of that computer to execute code encoded in the byte stream. In the case of a worm, this code will send the very same byte stream to other computers on the network, thereby creating an avalanche of network traffic that ultimately renders the network and all computers involved in replicating the worm inaccessible. Besides duplicating themselves, worms can alter data on the host that they are running on. The most famous example in recent years was the MSBlaster32 worm, which altered the configuration database on many Microsoft Windows machines, thereby forcing the computers to reboot incessantly. Although this worm was rather benign, it caused huge damage to businesses who were unable to use their IT infrastructure for hours or even days after the appearance of the worm. A more malicious worm is certainly conceivable [187] due to the fact that worms are executed as part of a dæmon (also known as "service" on Windows machines) and thereby run at a privileged level, allowing access to any data stored on the remote computer. While the deletion of data presents a looming threat to valuable information, even more serious uses are espionage and theft, in particular because worms do not have to affect the running system and hence may be impossible to detect.

A Performance Comparison of Tree and Ring Topologies in Distributed System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Min

A distributed system is a collection of computers that are connected via a communication network. Distributed systems have become commonplace due to the wide availability of low-cost, high performance computers and network devices. However, the management infrastructure often does not scale well when distributed systems get very large. Some of the considerations in building a distributed system are the choice of the network topology and the method used to construct the distributed system so as to optimize the scalability and reliability of the system, lower the cost of linking nodes together and minimize the message delay in transmission, and simplifymore » system resource management. We have developed a new distributed management system that is able to handle the dynamic increase of system size, detect and recover the unexpected failure of system services, and manage system resources. The topologies used in the system are the tree-structured network and the ring-structured network. This thesis presents the research background, system components, design, implementation, experiment results and the conclusions of our work. The thesis is organized as follows: the research background is presented in chapter 1. Chapter 2 describes the system components, including the different node types and different connection types used in the system. In chapter 3, we describe the message types and message formats in the system. We discuss the system design and implementation in chapter 4. In chapter 5, we present the test environment and results, Finally, we conclude with a summary and describe our future work in chapter 6.« less

Performance issues in management of the Space Station Information System

NASA Technical Reports Server (NTRS)

Johnson, Marjory J.

1988-01-01

The onboard segment of the Space Station Information System (SSIS), called the Data Management System (DMS), will consist of a Fiber Distributed Data Interface (FDDI) token-ring network. The performance of the DMS in scenarios involving two kinds of network management is analyzed. In the first scenario, how the transmission of routine management messages impacts performance of the DMS is examined. In the second scenario, techniques for ensuring low latency of real-time control messages in an emergency are examined.

Development and Implementation of the X.25 Protocol for the Universal Network Interface Device (UNID) II. Volume 1.

DTIC Science & Technology

1985-12-01

development of an improved Universal Network Interface Device (UNID II). The UNID II’s architecture was based on a preliminary design project at...interface device, performing all functions required ,: the multi-ring LAN. The device depicted by RADC’s studies would connect a highly variable group of host...used the ISO Open Systems Ilterconnection (OSI) seven layer model as the basic structure for data flow and program development . In 1982 Cuomo

Design of a network for concurrent message passing systems

NASA Astrophysics Data System (ADS)

Song, Paul Y.

1988-08-01

We describe the design of the network design frame (NDF), a self-timed routing chip for a message-passing concurrent computer. The NDF uses a partitioned data path, low-voltage output drivers, and a distributed token-passing arbiter to provide a bandwidth of 450 Mbits/sec into the network. Wormhole routing and bidirectional virtual channels are used to provide low latency communications, less than 2us latency to deliver a 216 bit message across the diameter of a 1K node mess-connected machine. To support concurrent software systems, the NDF provides two logical networks, one for user messages and one for system messages. The two networks share the same set of physical wires. To facilitate the development of network nodes, the NDF is a design frame. The NDF circuitry is integrated into the pad frame of a chip leaving the center of the chip uncommitted. We define an analytic framework in which to study the effects of network size, network buffering capacity, bidirectional channels, and traffic on this class of networks. The response of the network to various combinations of these parameters are obtained through extensive simulation of the network model. Through simulation, we are able to observe the macro behavior of the network as opposed to the micro behavior of the NDF routing controller.